Block-face imaging is a scanningelectron microscopic technique which enables easier acquisition of serial ultrastructural images directly from the surface of resin-embedded biological samples with a similar quality to transmission electron micrographs. In the present study, we analyzed the three-dimensional architecture of podocytes using serial block-face imaging. It was previously believed that podocytes are divided into three kinds of subcellular compartment: cell body, primary process, and foot process, which are simply aligned in this order. When the reconstructed podocytes were viewed from their basal side, the foot processes were branched from a ridge-like prominence, which was formed on the basal surface of the primary process and was similar to the usual foot processes in structure. Moreover, from the cell body, the foot processes were also emerged via the ridge-like prominence, as found in the primary process. The ridge-like prominence anchored the cell body and primary process to the glomerular basement membrane, and connected the foot processes to the cell body and primary process. In conclusion, serial block-face imaging is a powerful tool for clear understanding the three-dimensional architecture of podocytes through its ability to reveal novel structures which were difficult to determine by conventional transmission and scanningelectron microscopes alone. PMID:25759085

Serial blockface imaging with the scanningelectron microscope has been developed as an alternative to serial sectioning and transmission electron microscopy for the ultrastructural analysis of the three-dimensional organization of cells and tissues. An ultramicrotome within the microscope specimen chamber permits sectioning and imaging to a depth of many microns within resin-embedded specimens. The technology has only recently been adopted by plant microscopists and here we describe some specimen preparation procedures suitable for plant tissue, suggested microscope imaging parameters and discuss the software required for image reconstruction and analysis. PMID:27197647

Serial blockfacescanningelectron microscopy is rapidly becoming a popular tool for collecting large three-dimensional data sets of cells and tissues, filling the resolution and volume gap between fluorescence microscopy and high-resolution electron microscopy. The automated collection of data within the instrument occupies the smallest proportion of the time required to prepare and analyse biological samples. It is the processing of data once it has been collected that proves the greatest challenge. In this review we discuss different methods that are used to process data. We suggest potential workflows that can be used to facilitate the transfer of raw image stacks into quantifiable data as well as propose a set of criteria for reporting methods for data analysis to enable replication of work. PMID:26800017

Mechanical serial blockfacescanningelectron microscopy (SBFSEM) has emerged as a means of obtaining three dimensional (3D) electron images over volumes much larger than possible by focused ion beam (FIB) serial sectioning and at higher spatial resolution than achievable with conventional X-ray computed tomography (CT). Such high resolution 3D electron images can be employed for precisely determining the shape, volume fraction, distribution and connectivity of important microstructural features. While soft (fixed or frozen) biological samples are particularly well suited for nanoscale sectioning using an ultramicrotome, the technique can also produce excellent 3D images at electron microscope resolution in a time and resource-efficient manner for engineering materials. Currently, a lack of appreciation of the capabilities of ultramicrotomy and the operational challenges associated with minimising artefacts for different materials is limiting its wider application to engineering materials. Consequently, this paper outlines the current state of the art for SBFSEM examining in detail how damage is introduced during slicing and highlighting strategies for minimising such damage. A particular focus of the study is the acquisition of 3D images for a variety of metallic and coated systems. PMID:26855205

Human brain is a high energy consuming organ that mainly relies on glucose as a fuel source. Glucose is catabolized by brain mitochondria via glycolysis, tri-carboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS) pathways to produce cellular energy in the form of adenosine triphosphate (ATP). Impairment of mitochondrial ATP production causes mitochondrial disorders, which present clinically with prominent neurological and myopathic symptoms. Mitochondrial defects are also present in neurodevelopmental disorders (e.g. autism spectrum disorder) and neurodegenerative disorders (e.g. amyotrophic lateral sclerosis, Alzheimer's and Parkinson's diseases). Thus, there is an increased interest in the field for performing 3D analysis of mitochondrial morphology, structure and distribution under both healthy and disease states. The brain mitochondrial morphology is extremely diverse, with some mitochondria especially those in the synaptic region being in the range of <200 nm diameter, which is below the resolution limit of traditional light microscopy. Expressing a mitochondrially-targeted green fluorescent protein (GFP) in the brain significantly enhances the organellar detection by confocal microscopy. However, it does not overcome the constraints on the sensitivity of detection of relatively small sized mitochondria without oversaturating the images of large sized mitochondria. While serial transmission electron microscopy has been successfully used to characterize mitochondria at the neuronal synapse, this technique is extremely time-consuming especially when comparing multiple samples. The serial block-facescanningelectron microscopy (SBFSEM) technique involves an automated process of sectioning, imaging blocks of tissue and data acquisition. Here, we provide a protocol to perform SBFSEM of a defined region from rodent brain to rapidly reconstruct and visualize mitochondrial morphology. This technique could also be used to provide accurate information on

Serial block-face imaging using scanningelectron microscopy enables rapid observations of three-dimensional ultrastructures in a large volume of biological specimens. However, such imaging usually requires days for sample preparation to reduce charging and increase image contrast. In this study, we report a rapid procedure to acquire serial electron microscopic images within 1 day for three-dimensional analyses of subcellular ultrastructures. This procedure is based on serial block-face with two major modifications, including a new sample treatment device and direct polymerization on the rivets, to reduce the time and workload needed. The modified procedure without uranyl acetate can produce tens of embedded samples observable under serial block-facescanningelectron microscopy within 1 day. The serial images obtained are similar to the block-face images acquired by common procedures, and are applicable to three-dimensional reconstructions at a subcellular resolution. Using this approach, regional immune deposits and the double contour or heterogeneous thinning of basement membranes were observed in the glomerular capillary loops of an autoimmune nephropathy model. These modifications provide options to improve the throughput of three-dimensional electron microscopic examinations, and will ultimately be beneficial for the wider application of volume imaging in life science and clinical medicine. PMID:26867664

The zebrafish has emerged as an important model of heart development and regeneration. While the structural characteristics of the developing and adult zebrafish ventricle have been previously studied, little attention has been paid to the nature of the interface between the compact and spongy myocardium. Here we describe how these two distinct layers are structurally and functionally integrated. We demonstrate by transmission electron microscopy that this interface is complex and composed primarily of a junctional region occupied by collagen, as well as a population of fibroblasts that form a highly complex network. We also describe a continuum of uniquely flattened transitional cardiac myocytes that form a circumferential plate upon which the radially-oriented luminal trabeculae are anchored. In addition, we have uncovered within the transitional ring a subpopulation of markedly electron dense cardiac myocytes. At discrete intervals the transitional cardiac myocytes form contact bridges across the junctional space that are stabilized through localized desmosomes and fascia adherentes junctions with adjacent compact cardiac myocytes. Finally using serial block-facescanningelectron microscopy, segmentation and volume reconstruction, we confirm the three-dimensional nature of the junctional region as well as the presence of the sheet-like fibroblast network. These ultrastructural studies demonstrate the previously unrecognized complexity with which the compact and spongy layers are structurally integrated, and provide a new basis for understanding development and regeneration in the zebrafish heart. PMID:24058412

Cdc48p is a highly conserved cytosolic AAA chaperone that is involved in a wide range of cellular processes. It consists of two ATPase domains (D1 and D2), with regulatory regions at the N- and C-terminals. We have recently shown that Cdc48p regulates mitochondrial morphology, in that a loss of the ATPase activity or positive cooperativity in the D2 domain leads to severe fragmentations and aggregations of mitochondria in the cytoplasm. We have now used serial block-facescanningelectron microscopy (SBF-SEM), an advanced three-dimensional (3D) electron microscopic technique to examine the structures and morphological changes of mitochondria in the yeast Saccharomyces cerevisiae. We found that mutants lacking ATPase activity of Cdc48p showed mitochondrial fragmentations and aggregations, without fusion of the outer membrane. This suggests that the ATPase activity of Cdc48p is necessary for fusion of the outer membranes of mitochondria. Our results also show that SBF-SEM has considerable advantages in morphological and quantitative studies on organelles and intracellular structures in entire cells. PMID:24893221

The human malaria parasite, Plasmodium falciparum, exhibits morphological changes during the blood stage cycle in vertebrate hosts. Here, we used serial block-facescanningelectron microscopy (SBF-SEM) to visualize the entire structures of P. falciparum-infected red blood cells (iRBCs) and to examine their morphological and volumetric changes at different stages. During developmental stages, the parasite forms Maurer's clefts and vesicles in the iRBC cytoplasm and knobs on the iRBC surface, and extensively remodels the iRBC structure for proliferation of the parasite. In our observations, the Maurer's clefts and vesicles in the P. falciparum-iRBCs, resembling the so-called tubovesicular network (TVN), were not connected to each other, and continuous membrane networks were not observed between the parasitophorous vacuole membrane (PVM) and the iRBC cytoplasmic membrane. In the volumetric analysis, the iRBC volume initially increased and then decreased to the end of the blood stage cycle. This suggests that it is necessary to absorb a substantial amount of nutrients from outside the iRBC during the initial stage, but to release waste materials from inside the iRBC at the multinucleate stage. Transportation of the materials may be through the iRBC membrane, rather than a special structure formed by the parasite, because there is no direct connection between the iRBC membrane and the parasite. These results provide new insights as to how the malaria parasite grows in the iRBC and remodels iRBC structure during developmental stages; these observation can serve as a baseline for further experiments on the effects of therapeutic agents on malaria. PMID:26772147

The hippocampal mossy fiber (MF) terminal is among the largest and most complex synaptic structures in the brain. Our understanding of the development of this morphologically elaborate structure has been limited because of the inability of standard electron microscopy techniques to quickly and accurately reconstruct large volumes of neuropil. Here we use serial block-faceelectron microscopy (SBEM) to surmount these limitations and investigate the establishment of MF connectivity during mouse postnatal development. Based on volume reconstructions, we find that MF axons initially form bouton-like specializations directly onto dendritic shafts, that dendritic protrusions primarily arise independently of bouton contact sites, and that a dramatic increase in presynaptic and postsynaptic complexity follows the association of MF boutons with CA3 dendritic protrusions. We also identify a transient period of MF bouton filopodial exploration, followed by refinement of sites of synaptic connectivity. These observations enhance our understanding of the development of this highly specialized synapse and illustrate the power of SBEM to resolve details of developing microcircuits at a level not easily attainable with conventional approaches. PMID:23303931

The recently developed three-dimensional electron microscopic (EM) method of serial block-facescanningelectron microscopy (SBEM) has rapidly established itself as a powerful imaging approach. Volume EM imaging with this scanningelectron microscopy (SEM) method requires intense staining of biological specimens with heavy metals to allow sufficient back-scatter electron signal and also to render specimens sufficiently conductive to control charging artifacts. These more extreme heavy metal staining protocols render specimens light opaque and make it much more difficult to track and identify regions of interest (ROIs) for the SBEM imaging process than for a typical thin section transmission electron microscopy correlative light and electron microscopy study. We present a strategy employing X-ray microscopy (XRM) both for tracking ROIs and for increasing the efficiency of the workflow used for typical projects undertaken with SBEM. XRM was found to reveal an impressive level of detail in tissue heavily stained for SBEM imaging, allowing for the identification of tissue landmarks that can be subsequently used to guide data collection in the SEM. Furthermore, specific labeling of individual cells using diaminobenzidine is detectable in XRM volumes. We demonstrate that tungsten carbide particles or upconverting nanophosphor particles can be used as fiducial markers to further increase the precision and efficiency of SBEM imaging. PMID:25392009

The recently developed three-dimensional electron microscopic (EM) method of serial block-facescanningelectron microscopy (SBEM) has rapidly established itself as a powerful imaging approach. Volume EM imaging with this scanningelectron microscopy (SEM) method requires intense staining of biological specimens with heavy metals to allow sufficient back-scatter electron signal and also to render specimens sufficiently conductive to control charging artifacts. These more extreme heavy metal staining protocols render specimens light opaque and make it much more difficult to track and identify regions of interest (ROIs) for the SBEM imaging process than for a typical thin section transmission electron microscopy correlative light and electron microscopy study. We present a strategy employing X-ray microscopy (XRM) both for tracking ROIs and for increasing the efficiency of the workflow used for typical projects undertaken with SBEM. XRM was found to reveal an impressive level of detail in tissue heavily stained for SBEM imaging, allowing for the identification of tissue landmarks that can be subsequently used to guide data collection in the SEM. Furthermore, specific labeling of individual cells using diaminobenzidine is detectable in XRM volumes. We demonstrate that tungsten carbide particles or upconverting nanophosphor particles can be used as fiducial markers to further increase the precision and efficiency of SBEM imaging. PMID:25392009

The scanningelectron microscope equipped with an x-ray spectrometer is a versatile instrument which has many uses in the investigation of crime and preparation of scientific evidence for the courts. Major applications include microscopy and analysis of very small fragments of paint, glass and other materials which may link an individual with a scene of crime, identification of firearms residues and examination of questioned documents. Although simultaneous observation and chemical analysis of the sample is the most important feature of the instrument, other modes of operation such as cathodoluminescence spectrometry, backscattered electron imaging and direct x-ray excitation are also exploited. Marks on two bullets or cartridge cases can be compared directly by sequential scanning with a single beam or electronic linkage of two instruments. Particles of primer residue deposited on the skin and clothing when a gun is fired can be collected on adhesive tape and identified by their morphology and elemental composition. It is also possible to differentiate between the primer residues of different types of ammunition. Bullets may be identified from the small fragments left behind as they pass through the body tissues. In the examination of questioned documents the scanningelectron microscope is used to establish the order in which two intersecting ink lines were written and to detect traces of chemical markers added to the security inks on official documents.

IntroductionBecause recent three-dimensional (3D) ultrastructural reconstruction techniques such as serial blockfacescanningelectron microscopy (SBFSEM), obtain their images directly from the flat surface of specimens via material contrast[1], specimens should be strongly stained with heavy metals prior to resin embedding in order to obtain higher material contrast using backscattered electrons (BSEs). To enhance membrane contrast for blockface imaging (BFI), we usually stain specimens using the method published by Deerinck[2], and the images obtained show TEM-like contrast.However, recently, our research subjects have required reconstruction of a much larger volume, increasing the total image acquisition time. To reduce the total acquisition time, both high sensitivity detectors and a new specimen preparation method that provides much higher contrast are required. Takahashi et al.[3] have reported that hydroquinone (HQ) treatment during traditional electro-conductive staining increases specimen conductivity and drastically reduces the charge problem for SEM observation. They concluded that HQ treatment might increase the efficiency of secondary electron (SE) generation. Because BFI can be performed using SE as well as BSE, we examined whether addition of HQ treatment to en bloc staining protocols increased the contrast for BFI using SE. Materials & methodsMouse liver tissue was used. Mice were deeply anesthetized by diethyl ether and sodium pentobarbital, and tissues were fixed by transcardial perfusion of 2% paraformaldehyde and 2.5% glutaraldehyde in 0.1 M cacodylate buffer (pH 7.4) through the left ventricle, followed by heparin-containing saline. After perfusion, liver tissues were removed and cut into small cubes approximately 1 mm(3) in the fixative, and were further fixed in the same fixative for 2 h at 4°C. Subsequently, en blocstaining was performed as follows: the specimens were treated using a reduced-OTO staining method (1.5% potassium

A combination of two-dimensional (2D) and three-dimensional (3D) analyses of tissue volume ultrastructure acquired by serial blockfacescanningelectron microscopy can greatly shorten the time required to obtain quantitative information from big data sets that contain many billions of voxels. Thus, to analyse the number of organelles of a specific type, or the total volume enclosed by a population of organelles within a cell, it is possible to estimate the number density or volume fraction of that organelle using a stereological approach to analyse randomly selected 2D blockface views through the cells, and to combine such estimates with precise measurement of 3D cell volumes by delineating the plasma membrane in successive blockface images. The validity of such an approach can be easily tested since the entire 3D tissue volume is available in the serial blockfacescanningelectron microscopy data set. We have applied this hybrid 3D/2D technique to determine the number of secretory granules in the endocrine α and β cells of mouse pancreatic islets of Langerhans, and have been able to estimate the total insulin content of a β cell. PMID:26139222

Summary A combination of two‐dimensional (2D) and three‐dimensional (3D) analyses of tissue volume ultrastructure acquired by serial blockfacescanningelectron microscopy can greatly shorten the time required to obtain quantitative information from big data sets that contain many billions of voxels. Thus, to analyse the number of organelles of a specific type, or the total volume enclosed by a population of organelles within a cell, it is possible to estimate the number density or volume fraction of that organelle using a stereological approach to analyse randomly selected 2D blockface views through the cells, and to combine such estimates with precise measurement of 3D cell volumes by delineating the plasma membrane in successive blockface images. The validity of such an approach can be easily tested since the entire 3D tissue volume is available in the serial blockfacescanningelectron microscopy data set. We have applied this hybrid 3D/2D technique to determine the number of secretory granules in the endocrine α and β cells of mouse pancreatic islets of Langerhans, and have been able to estimate the total insulin content of a β cell. PMID:26139222

Two devices are described to aid in trimming blockfaces of embedded tissue for ultramicrotomy. The first, a reticle to fit the ocular of a stereomicroscope, can be manufactured by the ultramicrotomist and is designed to outline the edges of the blockface so that it can be trimmed to a standard size and shape with the area of interest centered in it. The second, a rectangular "trimalign" block mounted in the knife holder of the ultramicrotome, is, with the blockface, aligned to the plane of sectioning, and aids in retrimming the top and bottom edges of the blockface. This is the simplest trimming device yet described and the first which will, from any sort of embedded material, produce a blockface with parallel top and bottom edges even if the blockface is not perpendicular to the axis of the specimen holder. If the edge of the diamond knife used for sectioning is parallel to the axis of rotation of the knife holder, the blockface has also been automatically aligned to the kinfe as a consequence of this aligning and trimming procedure. As a result, sectioning can begin immediately without further adjustments. PMID:694954

We have applied serial block-facescanningelectron microscopy (SBF-SEM) to measure parameters that describe the architecture of pancreatic islets of Langerhans, microscopic endocrine organs that secrete insulin and glucagon for control of blood glucose. By analyzing entire mouse islets, we show that it is possible to determine (1) the distributions of alpha and beta cells, (2) the organization of blood vessels and pericapillary spaces, and (3) the ultrastructure of the individual secretory cells. Our results show that the average volume of a beta cell is nearly twice that of an alpha cell, and the total mitochondrial volume is about four times larger. In contrast, nuclear volumes in the two cell types are found to be approximately equal. Although the cores of alpha and beta secretory granules have similar diameters, the beta granules have prominent halos resulting in overall diameters that are twice those of alpha granules. Visualization of the blood vessels revealed that every secretory cell in the islet is in contact with the pericapillary space, with an average contact area of 9 ± 5% of the cell surface area. Our data show that consistent results can be obtained by analyzing small numbers of islets. Due to the complicated architecture of pancreatic islets, such precision cannot easily be achieved by using TEM of thin sections. PMID:25448885

Scattered radiation degrades contrast and signal-to-noise ratio of an x-ray image. If an image intensifier is used as the image receptor, scattering of light photons and electrons within the image intensifier, optical system, and video camera produces veiling glare. anti-scatter grids, air gaps, and paired scanning slits have been used for rejection of scattered radiation. However, none of these methods is effective against veiling glare, because veiling glare is generated after the radiation has passed through any of these anti-scatter devices. In chapter 1 is introduced an innovative approach for highly efficient rejection of both scattered radiation and veiling glare in digital fluorography. This method has been named electronic collimation, and the x-ray imaging technique based upon it is called electronicscanning-slit fluorography. It involves replacing paired fore and aft slits for scatter rejection with only one beam-defining tantalum fore aperture. As this aperture scans across the portion of the patient to be imaged, pulsed x-ray exposures produce images which are digitized and stored in the computer memory. Since the video signal within the projection of the aperture on the image intensifier is much more intense than behind the tantalum, one can discriminate electronically between these two signals and thus eliminate the unwanted x-ray scatter and veiling glare. Such electronic collimation does not require synchronization between the slit scanning and detector readout, which makes it much simpler than alternative methods and potentially adaptable to any digital fluorography system. Theoretical considerations relevant for the construction and evaluation of a prototype unit for electronicscanning slit fluorography are presented in Chapter 2. This chapter consists of four sections. In the first section 'Principles of image detection' the concepts of quantum efficiency and detective quantum efficiency (DQE) are introduced as the most meaningful way to

The Uninhabited Airborne Vehicle Synthetic Aperture Radar (UAVSAR) is a pod-based, L-band (1.26 GHz), repeatpass, interferometric, synthetic aperture radar (InSAR) used for Earth science applications. Repeat-pass interferometric radar measurements from an airborne platform require an antenna that can be steered to maintain the same angle with respect to the flight track over a wide range of aircraft yaw angles. In order to be able to collect repeat-pass InSAR data over a wide range of wind conditions, UAVSAR employs an active electronicallyscanned array (AESA). During data collection, the UAVSAR flight software continuously reads the aircraft attitude state measured by the Embedded GPS/INS system (EGI) and electronically steers the beam so that it remains perpendicular to the flight track throughout the data collection

Three-dimensional electron microscopy tools have revolutionized our understanding of cell structure and molecular complexes in biology. Here, we describe methods for studying flagellar ultrastructure and biogenesis in two unicellular parasites—Trypanosoma brucei and Leishmania mexicana. We describe methods for the preparation of these parasites for scanningelectron microscopy cellular electron tomography, and serial blockfacescanningelectron microscopy (SBFSEM). These parasites have a highly ordered cell shape and form, with a defined positioning of internal cytoskeletal structures and organelles. We show how knowledge of these can be used to dissect cell cycles in both parasites and identify the old flagellum from the new in T. brucei. Finally, we demonstrate the use of SBFSEM three-dimensional models for analysis of individual whole cells, demonstrating the excellent potential this technique has for future studies of mutant cell lines. PMID:25837406

Scanning array was designed with properties of low RF loss and phase control. The array consists of a series of special waveguides, hybrids made up of two variable reactance branch arms for input signals, an edge slot for the difference port, and a sum arm for the unradiated signal.

Images from scanningelectron microscopy are now quite common and they can be of great value in archaeology. Techniques such as secondary electron imaging, backscattered electron imaging and energy-dispersive x-ray analysis can reveal information such as the presence of weevils in grain in Roman Britain, the composition of Roman coins and the…

A new method for the image acquisition in scanningelectron microscopy (SEM) was introduced. The method used adaptively increased pixel-dwell times to improve the signal-to-noise ratio (SNR) in areas of high detail. In areas of low detail, the electron dose was reduced on a per pixel basis, and a-posteriori image processing techniques were applied to remove the resulting noise. The technique was realized by scanning the sample twice. The first, quick scan used small pixel-dwell times to generate a first, noisy image using a low electron dose. This image was analyzed automatically, and a software algorithm generated a sparse pattern of regions of the image that require additional sampling. A second scan generated a sparse image of only these regions, but using a highly increased electron dose. By applying a selective low-pass filter and combining both datasets, a single image was generated. The resulting image exhibited a factor of ≈3 better SNR than an image acquired with uniform sampling on a Cartesian grid and the same total acquisition time. This result implies that the required electron dose (or acquisition time) for the adaptive scanning method is a factor of ten lower than for uniform scanning. PMID:27150131

A new method for the image acquisition in scanningelectron microscopy (SEM) was introduced. The method used adaptively increased pixel-dwell times to improve the signal-to-noise ratio (SNR) in areas of high detail. In areas of low detail, the electron dose was reduced on a per pixel basis, and a-posteriori image processing techniques were applied to remove the resulting noise. The technique was realized by scanning the sample twice. The first, quick scan used small pixel-dwell times to generate a first, noisy image using a low electron dose. This image was analyzed automatically, and a software algorithm generated a sparse pattern of regions of the image that require additional sampling. A second scan generated a sparse image of only these regions, but using a highly increased electron dose. By applying a selective low-pass filter and combining both datasets, a single image was generated. The resulting image exhibited a factor of ≈3 better SNR than an image acquired with uniform sampling on a Cartesian grid and the same total acquisition time. This result implies that the required electron dose (or acquisition time) for the adaptive scanning method is a factor of ten lower than for uniform scanning. PMID:27150131

A new method for the image acquisition in scanningelectron microscopy (SEM) was introduced. The method used adaptively increased pixel-dwell times to improve the signal-to-noise ratio (SNR) in areas of high detail. In areas of low detail, the electron dose was reduced on a per pixel basis, and a-posteriori image processing techniques were applied to remove the resulting noise. The technique was realized by scanning the sample twice. The first, quick scan used small pixel-dwell times to generate a first, noisy image using a low electron dose. This image was analyzed automatically, and a software algorithm generated a sparse pattern of regions of the image that require additional sampling. A second scan generated a sparse image of only these regions, but using a highly increased electron dose. By applying a selective low-pass filter and combining both datasets, a single image was generated. The resulting image exhibited a factor of ≈3 better SNR than an image acquired with uniform sampling on a Cartesian grid and the same total acquisition time. This result implies that the required electron dose (or acquisition time) for the adaptive scanning method is a factor of ten lower than for uniform scanning.

Scannedelectron beams are used within many industries for applications such as sterilization of medical disposables, crosslinking of wire and cables insulating jackets, polymerization and degradation of resins and biomaterials, modification of semiconductors, coloration of gemstones and glasses, removal of oxides from coal plant flue gasses, and the curing of advanced composites and other molded forms. X-rays generated from scannedelectron beams make yet other applications, such as food irradiation, viable. Typical accelerators for these applications range in beam energy from 0.5MeV to 10 MeV, with beam powers between 5 to 500kW and scanning widths between 20 and 300 cm. Since precise control of dose delivery is required in many of these applications, the integration of beam characteristics, product conveyance, and beam scanning mechanisms must be well understood and optimized. Fundamental issues and some case examples are presented.

Early embryonic heart development is a period of dynamic growth and remodeling, with rapid changes occurring at the tissue, cell, and subcellular levels. A detailed understanding of the events that establish the components of the heart wall has been hampered by a lack of methodologies for three dimensional (3D), high-resolution imaging. Focused ion beam-scanningelectron microscopy (FIB-SEM) is a novel technology for imaging 3D tissue volumes at the subcellular level. FIB-SEM alternates between imaging the blockface with a scanningelectron beam and milling away thin sections of tissue with a focused ion beam, allowing for collection and analysis of 3D data. FIB-SEM was used to image the three layers of the day 4 chicken embryo heart: myocardium, cardiac jelly, and endocardium. Individual images obtained with FIB-SEM were comparable in quality and resolution to those obtained with transmission electron microscopy (TEM). Up to 1100 serial images were obtained in 4 nm increments at 4.88 nm resolution, and image stacks were aligned to create volumes 800–1500 μm3 in size. Segmentation of organelles revealed their organization and distinct volume fractions between cardiac wall layers. We conclude that FIB-SEM is a powerful modality for 3D subcellular imaging of the embryonic heart wall. PMID:24742339

Scanningelectron microscopy is a powerful tool to study the morphology of bacteria. We have used conventional scanningelectron microscope to follow the modification of the bacterial morphology over the course of the bacterial growth cycle. The bacteria were fixed in vapors of Glutaraldehyde and ruthenium oxide applied in sequence. A gold film of about 5 nm was deposited on top of the samples to avoid charging and to enhance the contrast. We have selected two types of bacteria Alcaligenes faecalis and Kocuria rhizophila. Their development was carefully monitored and samples were taken for imaging in equal time intervals during their cultivation. These studies are supporting our efforts to develop an optical method for identification of the Gram-type of bacterial cultures.

Array of pressure sensors operates reliably and repeatably over wide temperature range, extending from normal boiling point of water down to boiling point of nitrogen. Sensors accurate and repeat to within 0.1 percent. Operate for 12 months without need for recalibration. Array scannedelectronically, sensor readings multiplexed and sent to desktop computer for processing and storage. Used to measure distributions of pressure in research on boundary layers at high Reynolds numbers, achieved by low temperatures.

Superficial white onychomycosis is characterized by opaque, friable, whitish superficial spots on the nail plate. We examined an affected halux nail of a 20-year-old male patient with scanningelectron microscopy. The mycological examination isolated Trichophyton mentagrophytes. Abundant hyphae with the formation of arthrospores were found on the nail's surface, forming small fungal colonies. These findings showed the great capacity for dissemination of this form of onychomycosis. PMID:26560225

Scanningelectron microscopic (SEM) autoradiography of the lung is being used to determine the distribution of inhaled, alpha particle-emitting, plutonium dioxide particles. SEM autoradiography provides high visual impact views of alpha activity. Particles irradiating the bronchiolar epithelium were detected both on the bronchiolar surface and in peribronchiolar alveoli. The technique is being used to obtain quantitative data on the clearance rates of plutonium particles from bronchi and bronchioles.

Superficial white onychomycosis is characterized by opaque, friable, whitish superficial spots on the nail plate. We examined an affected halux nail of a 20-year-old male patient with scanningelectron microscopy. The mycological examination isolated Trichophyton mentagrophytes. Abundant hyphae with the formation of arthrospores were found on the nail's surface, forming small fungal colonies. These findings showed the great capacity for dissemination of this form of onychomycosis. PMID:26560225

Scanningelectron microscopes are useful biological tools that can be used to image the surface of whole organisms, tissues, cells, cellular components, and macromolecules. Processes and structures that exist at surfaces can be imaged in pseudo, or real 3D at magnifications ranging from about 10× to 1,000,000×. Therefore a whole multicellular organism, such as a fly, or a single protein embedded in one of its cell membranes can be visualized. In order to identify that protein at high resolution, or to see and quantify its distribution at lower magnifications, samples can be labeled with antibodies. Any surface that can be exposed can potentially be studied in this way. Presented here is a generic method for immunogold labeling for scanningelectron microscopy, using two examples of specimens: isolated nuclear envelopes and the cytoskeleton of mammalian culture cells. Various parameters for sample preparation, fixation, immunogold labeling, drying, metal coating, and imaging are discussed so that the best immunogold scanningelectron microscopy results can be obtained from different types of specimens. PMID:27515090

A case of ringed hair studied by light and electron microscopy is reported. The patient, a 20-year old girl, had been presenting with the hair abnormality since birth. At naked eye examination the hairs were dry, 6 to 7 cm long, and they showed dull and shining areas giving the scalp hair a scintillating appearance (fig. 1). Several samples of hair were taken and examined by light microscopy under white and polarized light. Hair shafts and cryo-fractured surfaces were examined by scanningelectron microscopy. RESULTS. 1. Light microscopy. Lesions were found in every hair examined. There were abnormal, opaque and fusiform areas alternating with normal areas all along the hair shaft (fig. 2). The abnormal areas resulted from intracortical air-filled cavities. Fractures similar to those of trichorrhexis nodosa were found in the opaque areas of the distal parts of the hairs. 2. Scanningelectron microscopy. A. Hair shaft surface. The abnormal areas showed a longitudinal, "curtain-like" folding of the cuticular cells which had punctiform depressions on their surface and worn free edges (fig. 4, 5, 6); trichorrhexis-type fractures were seen in the distal parts of the hair shafts (fig. 7, 8). Normal areas regularly presented with longitudinal, superficial, short and non-systematized depressions (fig. 9); the cuticular cells were worn, and there were places where the denuded cortex showed dissociated cortical fibres (fig. 10).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3415147

The ScanningElectron Microscope (SEM) is used extensively to characterize and analyze wear mechanisms and coatings on material. Wear mechanisms and severity can be identified by the characteristic scars on sample surfaces and by examining wear debris. Backscattered electron imaging is very useful in identifying oxidized materials and locations where coatings have worn thin. These images are compared with spectra from energy-dispersive X-ray spectroscopy or wavelength-dispersive spectroscopy data to verify the identifications. Micrographs of typical wear mechanisms are presented and techniques for analysis of wear surfaces are discussed. Examples of the evaluation of coatings are also presented and an ultramicrohardness tester installed in the SEM to evaluate coating hardness and fracture toughness is described. 3 refs., 15 figs.

We evaluated treatment with hexamethyldisilazane (HMDS) as an alternative to critical-point drying (CPD) for preparing microscopic Gastrotricha for scanningelectron microscopy (SEM). We prepared large marine (2 mm) and small freshwater (100 microm) gastrotrichs using HMDS as the primary dehydration solvent and compared the results to earlier investigations using CPD. The results of HMDS dehydration are similar to or better than CPD for resolution of two important taxonomic features: cuticular ornamentation and patterns of ciliation. The body wall of both sculpted (Lepidodermella) and smooth (Dolichodasys) gastrotrichs retained excellent morphology as did the delicate sensory and locomotory cilia. The only unfavorable result of HMDS dehydration was an occasional coagulation of gold residue when the solvent had not fully evaporated before sputter-coating. We consider HMDS an effective alternative for preparing of gastrotrichs for SEM because it saves time and expense compared to CPD. PMID:10810982

The electric field distribution and charging effects in ScanningElectron Microscopy (SEM) were studied by extending a Monte-Carlo based SEM simulator by a fast and accurate multigrid (MG) based 3D electric field solver. The main focus is on enabling short simulation times with maintaining sufficient accuracy, so that SEM simulation can be used in practical applications. The implementation demonstrates a gain in computation speed, when compared to a Gauss-Seidel based reference solver is roughly factor of 40, with negligible differences in the result (~10-6 𝑉). In addition, the simulations were compared with experimental SEM measurements using also complex 3D sample, showing that i) the modelling of e-fields improves the simulation accuracy, and ii) multigrid method provide a significant benefit in terms of simulation time.

Consideration is given to a cryogenic multichannel electronicallyscanned pressure (ESP) module developed and tested over an extended temperature span from -184 to +50 C and a pressure range of 0 to 5 psig. The ESP module consists of 32 pressure sensor dice, four analog 8 differential-input multiplexers, and an amplifier circuit, all of which are packaged in a physical volume of 2 x 1 x 5/8 in with 32 pressure and two reference ports. Maximum nonrepeatability is measured at 0.21 percent of full-scale output. The ESP modules have performed consistently well over 15 times over the above temperature range and continue to work without any sign of degradation. These sensors are also immune to repeated thermal shock tests over a temperature change of 220 C/sec.

Tinea nigra is a rare superficial mycosis caused by Hortaea werneckii. This infection presents as asymptomatic brown to black maculae mostly in palmo-plantar regions. We performed scanningelectron microscopy of a superficial shaving of a tinea nigra lesion. The examination of the outer surface of the sample showed the epidermis with corneocytes and hyphae and elimination of fungal filaments. The inner surface of the sample showed important aggregation of hyphae among keratinocytes, which formed small fungal colonies. The ultrastructural findings correlated with those of dermoscopic examination - the small fungal aggregations may be the dark spicules seen on dermoscopy - and also allowed to document the mode of dissemination of tinea nigra, showing how hyphae are eliminated on the surface of the lesion. PMID:24770516

The scanning-transmission imaging mode in the SEM allows for the threedimensional tomographic reconstruction of a specimen, starting from a set of projection images. Compressed sensing was used to solve the undetermined problem of structure reconstruction and was proven capable of overcoming the limitations arising from the sampling scheme. Reconstructions of cobalt particles within a carbon nanotube and collagen fibrils in a dermal tissue are presented, demonstrating the potential of this technique in the set of 3-D electron microscopy methods for both physical and biological science.

Three-dimensional simulations of the trajectories of secondary electrons (SE) in the scanningelectron microscope have been performed for plenty of real configurations of the specimen chamber, including all its basic components. The primary purpose was to evaluate the collection efficiency of the Everhart-Thornley detector of SE and to reveal fundamental rules for tailoring the set-ups in which efficient signal acquisition can be expected. Intuitive realizations about the easiness of attracting the SEs towards the biased front grid of the detector have shown themselves likely as false, and all grounded objects in the chamber have been proven to influence the spatial distribution of the signal-extracting field. The role of the magnetic field penetrating from inside the objective lens is shown to play an ambiguous role regarding possible support for the signal collection. PMID:17063762

A scanning transmission electron microscopy (STEM) system is disclosed. The system may make use of an electron beam scanning system configured to generate a plurality of electron beam scans over substantially an entire sample, with each scan varying in electron-illumination intensity over a course of the scan. A signal acquisition system may be used for obtaining at least one of an image, a diffraction pattern, or a spectrum from the scans, the image, diffraction pattern, or spectrum representing only information from at least one of a select subplurality or linear combination of all pixel locations comprising the image. A dataset may be produced from the information. A subsystem may be used for mathematically analyzing the dataset to predict actual information that would have been produced by each pixel location of the image.

Digital images captured with electron microscopes are corrupted by two fundamental effects: shot noise resulting from electron counting statistics and blur resulting from the nonzero width of the focused electron beam. The generic problem of computationally undoing these effects is called image reconstruction and for decades has proved to be one of the most challenging and important problems in imaging science. This proposal concerned the application of the Pixon method, the highest-performance image-reconstruction algorithm yet devised, to the enhancement of images obtained from the highest-resolution electron microscopes in the world, now in operation at Oak Ridge National Laboratory.

Unwanted motion of the probe with respect to the sample is a ubiquitous problem in scanning probe and scanning transmission electron microscopies, causing both linear and nonlinear artifacts in experimental images. We have designed a procedure to correct these artifacts by using orthogonal scan pairs to align each measurement line-by-line along the slow scan direction, by fitting contrast variation along the lines. We demonstrate the accuracy of our algorithm on both synthetic and experimental data and provide an implementation of our method. PMID:26716724

Electronic and nanostructured materials have been investigated using advanced scanning transmission electron microscopy (STEM) techniques. The first topic is the microstructure of Ga and Sb-doped ZnO. Ga-doped ZnO is a candidate transparent conducting oxide material. The microstructure of GZO thin films grown by MBE under different growth conditions and different substrates were examined using various electron microscopy (EM) techniques. The microstructure, prevalent defects, and polarity in these films strongly depend on the growth conditions and substrate. Sb-doped ZnO nanowires have been shown to be the first route to stable p-type ZnO. Using Z-contrast STEM, I have showed that an unusual microstructure of Sb-decorated head-to-head inversion domain boundaries and internal voids contain all the Sb in the nanowires and cause the p-type conduction. InGaN thin films and InGaN / GaN quantum wells (QW) for light emitting diodes are the second topic. Low-dose Z-contrast STEM, PACBED, and EDS on InGaN QW LED structures grown by MOCVD show no evidence for nanoscale composition variations, contradicting previous reports. In addition, a new extended defect in GaN and InGaN was discovered. The defect consists of a faceted pyramid-shaped void that produces a threading dislocation along the [0001] growth direction, and is likely caused by carbon contamination during growth. Non-rigid registration (NRR) and high-precision STEM of nanoparticles is the final topic. NRR is a new image processing technique that corrects distortions arising from the serial nature of STEM acquisition that previously limited the precision of locating atomic columns and counting the number of atoms in images. NRR was used to demonstrate sub-picometer precision in STEM images of single crystal Si and GaN, the best achieved in EM. NRR was used to measure the atomic surface structure of Pt nanoacatalysts and Au nanoparticles, which revealed new bond length variation phenomenon of surface atoms. In

Based on a scanningelectron microscope operated at 30 kV with a homemade specimen holder and a multiangle solid-state detector behind the sample, low-kV scanning transmission electron microscopy (STEM) is presented with subsequent electron tomography for three-dimensional (3D) volume structure. Because of the low acceleration voltage, the stronger electron-atom scattering leads to a stronger contrast in the resulting image than standard TEM, especially for light elements. Furthermore, the low-kV STEM yields less radiation damage to the specimen, hence the structure can be preserved. In this work, two-dimensional STEM images of a 1-μm-thick cell section with projection angles between ±50° were collected, and the 3D volume structure was reconstructed using the simultaneous iterative reconstructive technique algorithm with the TomoJ plugin for ImageJ, which are both public domain software. Furthermore, the cross-sectional structure was obtained with the Volume Viewer plugin in ImageJ. Although the tilting angle is constrained and limits the resulting structural resolution, slicing the reconstructed volume generated the depth profile of the thick specimen with sufficient resolution to examine cellular uptake of Au nanoparticles, and the final position of these nanoparticles inside the cell was imaged. PMID:23026379

The Uninhabited Airborne Vehicle Synthetic Aperture Radar (UAVSAR) L-band (1.2-1.3 GHz) repeat pass, interferometric synthetic aperture radar (InSAR) used for Earth science applications. Using complex radar images collected during separate passes on time scales of hours to years, changes in surface topography can be measured. The repeat-pass InSAR technique requires that the radar look angle be approximately the same on successive passes. Due to variations in aircraft attitude between passes, antenna beam steering is required to replicate the radar look angle. This paper describes an active, electronically steered array (AESA) that provides beam steering capability in the antenna azimuth plane. The array contains 24 transmit/receive modules generating 2800 W of radiated power and is capable of pulse-to-pulse beam steering and polarization agility. Designed for high reliability as well as serviceability, all array electronics are contained in single 178cm x 62cm x 12 cm air-cooled panel suitable for operation up 60,000 ft altitude.

Serial blockface imaging is a microscopy technique in which the top of a specimen is cut or ground away and a mosaic of images is collected of the newly revealed cross-section. Images collected from each slice are then digitally stacked to achieve 3D images. The development of fully automated image acquisition devices has made serial blockface imaging more attractive by greatly reducing labour requirements. The technique is particularly attractive for studies of biological activity within cancellous bone as it has the capability of achieving direct, automated measures of biological and morphological traits and their associations with one another. When used with fluorescence microscopy, serial blockface imaging has the potential to achieve 3D images of tissue as well as fluorescent markers of biological activity. Epifluorescence-based serial blockface imaging presents a number of unique challenges for visualizing bone specimens due to noise generated by sub-surface signal and local variations in tissue autofluorescence. Here we present techniques for processing serial blockface images of trabecular bone using a combination of non-uniform illumination correction, precise tiling of the mosaic in each cross-section, cross-section alignment for vertical stacking, removal of sub-surface signal and segmentation. The resulting techniques allow examination of bone surface texture that will enable 3D quantitative measures of biological processes in cancellous bone biopsies. PMID:19772536

A scanningelectron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning it with a focused beam of electrons. The electrons interact with the sample atoms, producing various signals that are collected by detectors. The gathered signals contain information about the sample's surface topography and composition. The electron beam is generally scanned in a raster scan pattern, and the beam's position is combined with the detected signal to produce an image. The most common configuration for an SEM produces a single value per pixel, with the results usually rendered as grayscale images. The captured images may be produced with insufficient brightness, anomalous contrast, jagged edges, and poor quality due to low signal-to-noise ratio, grained topography and poor surface details. The segmentation of the SEM images is a tackling problems in the presence of the previously mentioned distortions. In this paper, we are stressing on the clustering of these type of images. In that sense, we evaluate the performance of the well-known unsupervised clustering and classification techniques such as connectivity based clustering (hierarchical clustering), centroid-based clustering, distribution-based clustering and density-based clustering. Furthermore, we propose a new spatial fuzzy clustering technique that works efficiently on this type of images and compare its results against these regular techniques in terms of clustering validation metrics.

We demonstrate a scanningelectron nanobeam diffraction technique that can be used for mapping the size and distribution of nanoscale crystalline regions in a polymer blend. In addition, it can map the relative orientation of crystallites and the degree of crystallinity of the material. The model polymer blend is a 50:50w/w mixture of semicrystalline poly(3-hexylthiophene-2,5-diyl) (P3HT) and amorphous polystyrene (PS). The technique uses a scanningelectron beam to raster across the sample and acquires a diffraction image at each probe position. Through image alignment and filtering, the diffraction image dataset enables mapping of the crystalline regions within the scanned area and construction of an orientation map. PMID:27323282

A recently developed in vitro excystation procedure results in almost total excystation of Giardia muris, an intestinal parasite of mice. The present experiment examines the G. muris cyst morphology by scanningelectron microscopy and evaluates the efficacy of the excystation pro...

Forty stainless steel endodontic files were observed at scanningelectron microscopy after being subjected to ten disinfection cycles of 10 minutes each one, immersed in different chemical disinfectants. Corrosion was not observed on the surface of the files in circumstances that this study was made. PMID:1659857

A simple apparatus for emulsion coating is described. The apparatus is inexpensive and easily assembled in a standard glass shop. Emulsion coating for scanningelectron microscope autoradiography with this apparatus consistently yields uniform layers. When used in conjunction with newly described fixation methods, this new approach produces reliable autoradiographs of undamaged specimens. PMID:6234956

The degradation of electrolytic tinplate used in food containers was analysed and evaluated, using scanningelectron microscopy and electrochemical measurements of microcorrosion and ion dissolution by atomic absorption to prevent food contamination caused by metal traces and to increase the durability of such tinplates. PMID:12627896

We have developed a new type of microscope possessing a unique feature of observing both scanningelectron and X-ray images under one unit. Unlike former X-ray microscopes using SEM [1, 2], this scanningelectron and X-ray (SELX) microscope has a sample in vacuum, thus it enables one to observe a surface structure of a sample by SEM mode, to search the region of interest, and to observe an X-ray image which transmits the region. For the X-ray observation, we have been focusing on the soft X-ray region from 280 eV to 3 keV to observe some bio samples and soft materials. The resolutions of SEM and X-ray modes are 50 nm and 100 nm, respectively, at the electron energy of 7 keV.

The exploration of remote planetary surfaces calls for the advancement of low power, highly-miniaturized instrumentation. Instruments of this nature that are capable of multiple types of analyses will prove to be particularly useful as we prepare for human return to the moon, and as we continue to explore increasingly remote locations in our Solar System. To this end, our group has been developing a miniaturized Environmental-ScanningElectron Microscope (mESEM) capable of remote investigations of mineralogical samples through in-situ topographical and chemical analysis on a fine scale. The functioning of an SEM is well known: an electron beam is focused to nanometer-scale onto a given sample where resulting emissions such as backscattered and secondary electrons, X-rays, and visible light are registered. Raster scanning the primary electron beam across the sample then gives a fine-scale image of the surface topography (texture), crystalline structure and orientation, with accompanying elemental composition. The flexibility in the types of measurements the mESEM is capable of, makes it ideally suited for a variety of applications. The mESEM is appropriate for use on multiple planetary surfaces, and for a variety of mission goals (from science to non-destructive analysis to ISRU). We will identify potential applications and range of potential uses related to planetary exploration. Over the past few of years we have initiated fabrication and testing of a proof-of-concept assembly, consisting of a cold-field-emission electron gun and custom high-voltage power supply, electrostatic electron-beam focusing column, and scanning-imaging electronics plus backscatter detector. Current project status will be discussed. This effort is funded through the NASA Research Opportunities in Space and Earth Sciences - Planetary Instrument Definition and Development Program.

Novel techniques to probe electronic properties at the nanoscale can shed light on the physics of nanoscale devices. In particular, studying the scattering of electrons from edges and apertures at the nanoscale and imaging the electron profile in a quantum dot, have been of interest [1]. In this paper, we present the design and implementation of a cooled scanning capacitance probe that operates at liquid He temperatures to image electron waves in nanodevices. The conducting tip of a scanned probe microscope is held above the nanoscale structure, and an applied sample-to-tip voltage creates an image charge that is measured by a cooled charge amplifier [2] adjacent to the tip. The circuit is based on a low-capacitance, high- electron-mobility transistor (Fujitsu FHX35X). The input is a capacitance bridge formed by a low capacitance pinched-off HEMT transistor and tip-sample capacitance. We have achieved low noise level (0.13 e/VHz) and high spatial resolution (100 nm) for this technique, which promises to be a useful tool to study electronic behavior in nanoscale devices.

The integration of low-temperature scanning-probe techniques and single-electron capacitance spectroscopy represents a powerful tool to study the electronic quantum structure of small systems - including individual atomic dopants in semiconductors. Here we present a capacitance-based method, known as Subsurface Charge Accumulation (SCA) imaging, which is capable of resolving single-electron charging while achieving sufficient spatial resolution to image individual atomic dopants. The use of a capacitance technique enables observation of subsurface features, such as dopants buried many nanometers beneath the surface of a semiconductor material1,2,3. In principle, this technique can be applied to any system to resolve electron motion below an insulating surface. As in other electric-field-sensitive scanned-probe techniques4, the lateral spatial resolution of the measurement depends in part on the radius of curvature of the probe tip. Using tips with a small radius of curvature can enable spatial resolution of a few tens of nanometers. This fine spatial resolution allows investigations of small numbers (down to one) of subsurface dopants1,2. The charge resolution depends greatly on the sensitivity of the charge detection circuitry; using high electron mobility transistors (HEMT) in such circuits at cryogenic temperatures enables a sensitivity of approximately 0.01 electrons/Hz½ at 0.3 K 5. PMID:23929222

Pseudomonas putida colonies were examined by scanningelectron microscope. A variety of cell morphologies, multicellular arrangements, and extracellular materials were observed in the fixed material. Different regions of a single colony showed characteristic organizations of these architectural elements. In some cases, the detailed microstructure of the fixed colony surfaces observed by scanningelectron microscopy could be correlated with macroscopic patterns visualized by histochemical staining and surface relief photography of live colonies. Extracellular materials were seen to extend onto the agar surface beyond the boundaries of the cell mass, and the final structures of these materials, after fixation and desiccation, were colony specific. The significance of these features of colony microstructure for formulating hypotheses about the control of colony morphogenesis is discussed. Images PMID:4066611

The scanningelectron microscope is becoming a popular tool to perform tasks that require positioning, manipulation, characterization, and assembly of micro-components. However, some of these applications require a higher level of performance with respect to dynamics and precision of positioning. One limiting factor is the presence of unidentified noises and disturbances. This work aims to study the influence of mechanical disturbances generated by the environment and by the microscope, identifying how these can affect elements in the vacuum chamber. To achieve this objective, a dedicated setup, including a high-resolution vibrometer, was built inside the microscope. This work led to the identification and quantification of main disturbances and noise sources acting on a scanningelectron microscope. Furthermore, the effects of external acoustic excitations were analysed. Potential applications of these results include noise compensation and real-time control for high accuracy tasks.

This is the extended project by introducing the modified dynamic range histogram modification (MDRHM) and is presented in this paper. This technique is used to enhance the scanningelectron microscope (SEM) imaging system. By comparing with the conventional histogram modification compensators, this technique utilizes histogram profiling by extending the dynamic range of each tile of an image to the limit of 0-255 range while retains its histogram shape. The proposed technique yields better image compensation compared to conventional methods. PMID:25969945

We demonstrate the feasibility of investigating periodically driven magnetization dynamics in a scanningelectron microscope with polarization analysis based on spin-polarized low-energy electron diffraction. With the present setup, analyzing the time structure of the scattering events, we obtain a temporal resolution of 700 ps, which is demonstrated by means of imaging the field-driven 100 MHz gyration of the vortex in a soft-magnetic FeCoSiB square. Owing to the efficient intrinsic timing scheme, high-quality movies, giving two components of the magnetization simultaneously, can be recorded on the time scale of hours.

The surface morphology of larval and adult Trichinella spiralis was studied by scanningelectron microscopy (SEM) of fixed, dried, and metal-coated specimens. The results are compared with those found earlier by various investigators using light and transmission electron microscopy. Some morphological features reported here are revealed uniquely by SEM. These include the pores of the cephalic sense organs, the character of secondary cuticular folds, variations of the hypodermal gland cell openings or pores, and the presence of particles on the copulatory bell.

This work presents recent advances in transmission scanningelectron microscopy (t-SEM) imaging control capabilities. A modular aperture system and a cantilever-style sample holder that enable comprehensive angular selectivity of forward-scattered electrons are described. When combined with a commercially available solid-state transmission detector having only basic bright-field and dark-field imaging capabilities, the advances described here enable numerous transmission imaging modes. Several examples are provided that demonstrate how contrast arising from diffraction to mass-thickness can be obtained. Unanticipated image contrast at some imaging conditions is also observed and addressed. PMID:27179301

This paper proposes a fast new technique for restoring scanningelectron microscope images to improve their sharpness. The images with our approach are sharpened by deconvolution with the point spread function modeled as the intensity distribution of the electron beam at the specimen's surface. We propose an iterative technique that employs a modified cost function based on the Richardson-Lucy method to achieve faster processing. The empirical results indicate significant improvements in image quality. The proposed approach speeds up deconvolution by about 10-50 times faster than that with the conventional Richardson-Lucy method.

We present a technique based on scanning transmission electron microscopy (STEM) that is capable of probing nanobubble dynamics with nanometer spatial resolution. A vacuum-tight vessel holds a sub-micrometer layer of water between two electron-transparent dielectric membranes. Electrical current pulses passing through a platinum wire on one of the membranes inject sufficient heat locally to initiate single bubble formation. In the absence of power input, all bubbles are observed to be unstable against collapse, but the STEM beam alone can cause a shrinking bubble to grow.

Scanningelectron microscopy (SEM) is used to evaluate potential chromosome preparations and staining methods for application in high-resolution three-dimensional X-ray imaging. Our starting point is optical fluorescence microscopy, the standard method for chromosomes, which only gives structural detail at the 200 nm scale. In principle, with suitable sample preparation protocols, including contrast enhancing staining, the surface structure of the chromosomes can be viewed at the 1 nm level by SEM. Here, we evaluate a heavy metal nucleic-acid-specific stain, which gives strong contrast in the backscattered electron signal. This study uses SEM to examine chromosomes prepared in different ways to establish a sample preparation protocol for X-rays. Secondary electron and backscattered electron signals are compared to evaluate the effectiveness of platinum-based stains used to enhance the contrast. PMID:24470422

Immunogold labeling (IGL) technique has been utilized by many authors in combination with scanningelectron microscopy (SEM) and transmission electron microscopy (TEM) to obtain the identification/localization of receptors and antigens, both in cells and tissues. Environmental scanningelectron microscopy (ESEM) represents an important tool in biomedical research, since it does not require any severe processing of the sample, lowering the risk of generating artifacts and interfere with the IGL procedure. The absence of metal coating could yield further advantages for our purpose as the labeling detection is based on the atomic number difference between nanogold spheres and the biological material. Using the gaseous secondary electron detector, compositional contrast is easily revealed by the backscattered electron component of the signal. In spite of this fact, only few published papers present a combination of ESEM and IGL. Hereby we present our method, optimized to improve the intensity and the specificity of the labeling signal, in order to obtain a semiquantitative evaluation of the labeling signal.In particular, we used a combination of IGL and ESEM to detect the presence of a protein on the cell surface. To achieve this purpose, we chose as an experimental system 3T3 Swiss albino mouse fibroblasts and galectin-3. PMID:23027021

A low-pass secondary electron detector has been invented for outlens scanningelectron microscopy. This detector is composed of a bias grid above and an electron detector below the specimen. The upward low-energy electrons emitted from the specimen are reflected downward by the bias grid and reach the secondary electron detector. The high-energy electrons penetrate the grid and are not detected. This detector has an advantage of quantitative analysis because the secondary electron trajectories are easily traced with simple parabolic motion. The energy-filtered images of the GaN/Si sample are obtained using this detector.

A miniaturized ScanningElectron Microscope (mSEM) for in-situ lunar investigations is being developed at NASA Marshall Space Flight Center with colleagues from the University of Alabama in Huntsville (UAH), Advanced Research Systems (ARS), the University of Tennessee in Knoxville (UTK) and Case Western Reserve University (CWRU). This effort focuses on the characterization of individual components of the mSEM and simulation of the complete system. SEMs can provide information on the size, shape, morphology and chemical composition of lunar regolith. Understanding these basic properties will allow us to better estimate the challenges associated with In-Situ Resource Utilization and to improve our basic science knowledge of the lunar surface (either precluding the need for sample return or allowing differentiation of unique samples to be returned to Earth.) The main components of the mSEM prototype includes: a cold field emission electron gun (CFEG), focusing lens, deflection/scanning system and backscatter electron detector. Of these, the electron gun development is of particular importance as it dictates much of the design of the remaining components. A CFEG was chosen for use with the lunar mSEM as its emission does not depend on heating of the tungsten emitter (lower power), it offers a long operation lifetime, is orders of magnitude brighter than tungsten hairpin guns, has a small source size and exhibits low beam energy spread.

Microorganisms, including bacteria, fungi, protozoa, and microalgae, are composed predominantly of water which prohibits direct observation in a traditional scanningelectron microscope (SEM). Preparation for SEM requires that microorganisms be fixed, frozen or dehydrated, and coated with a conductive film before observation in a high vacuum environment. Sample preparation may mechanically disturb delicate samples, compromise morphological information, and introduce other artifacts. The environmental scanningelectron microscope (ESEM) provides a technology for imaging hydrated or dehydrated biological samples with minimal manipulation and without the need for conductive coatings. Sporulating cultures of three fungi, Aspergillus sp., Cunninghamella sp., and Mucor sp., were imaged in the ESEM to assess usefulness of the instrument in the direct observation of delicate, uncoated, biological specimens. Asexual sporophores showed no evidence of conidial displacement or disruption of sporangia. Uncoated algal cells of Euglena gracilis and Spirogyra sp. were examined using the backscatter electron detector (BSE) and the environmental secondary electron detector (ESD) of the ESEM. BSE images had more clearly defined intracellular structures, whereas ESD gave a clearer view of the surface E. gracilis cells fixed with potassium permanganate, Spirogyra sp. stained with Lugol's solution, and Saprolegnia sp. fixed with osmium tetroxide were compared using BSE and ESD to demonstrate that cellular details could be enhanced by the introduction of heavy metals. The effect of cellular water on signal quality was evaluated by comparing hydrated to critical point dried specimens. PMID:8400431

30keV Ga(+) focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z(2), and shows a non-monotonic relationship between contrast and Z(2). The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion-solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanningelectron microscopy (SEM) also shows non-monotonic contrast as a function of Z(2), following the periodic behavior of the stopping power for electron-solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle-solid interaction theory. PMID:21939622

Low voltage scanningelectron microscopy is an important part of microelectronic inspection technique. This makes it possible to examine devices without changing the electrical properties, and to examine nonconducting samples such as photoresist without the use of a surface metal layer. The secondary electron imaging method suffers, however, from the difficulty that the image can be spoiled by slight charging of the specimen by the incident electron beam. This problem can be solved by the use of the low-loss electron image.

A new highly efficient design for semiconductor detectors of intermediate-energy electrons (1-50 keV) for application in scanningelectron microscopes is proposed. Calculations of the response function of advanced detectors and control experiments show that the efficiency of the developed devices increases on average twofold, which is a significant positive factor in the operation of modern electron microscopes in the mode of low currents and at low primary electron energies.

We developed a cryomicrotome/imaging system that provides high resolution, high sensitivity block-face images of whole mice or excised organs, and applied it to a variety of biological applications. With this cryo-imaging system, we sectioned cryo-preserved tissues at 2-40 μm thickness and acquired high resolution brightfield and fluorescence images with microscopic in-plane resolution (as good as 1.2 μm). Brightfield images of normal and pathological anatomy show exquisite detail, especially in the abdominal cavity. Multi-planar reformatting and 3D renderings allow one to interrogate 3D structures. In this report, we present brightfield images of mouse anatomy, as well as 3D renderings of organs. For BPK mice model of polycystic kidney disease, we compared brightfield cryo-images and kidney volumes to MRI. The color images provided greater contrast and resolution of cysts as compared to in vivo MRI. We note that color cryo-images are closer to what a researcher sees in dissection, making it easier for them to interpret image data. The combination of field of view, depth of field, ultra high resolution and color/fluorescence contrast enables cryo-image volumes to provide details that cannot be found through in vivo imaging or other ex vivo optical imaging approaches. We believe that this novel imaging system will have applications that include identification of mouse phenotypes, characterization of diseases like blood vessel disease, kidney disease, and cancer, assessment of drug and gene therapy delivery and efficacy and validation of other imaging modalities.

Several instrumental imperfections of transmission electron microscopes are characterized and their effects on the results of quantitative scanningelectron microscopy (STEM) are investigated and quantified using simulations. Methods to either avoid influences of these imperfections during acquisition or to include them in reference calculations are proposed. Particularly, distortions inflicted on the diffraction pattern by an image-aberration corrector can cause severe errors of more than 20% if not accounted for. A procedure for their measurement is proposed here. Furthermore, afterglow phenomena and nonlinear behavior of the detector itself can lead to incorrect normalization of measured intensities. Single electrons accidentally impinging on the detector are another source of error but can also be exploited for threshold-less calibration of STEM images to absolute dose, incident beam current determination and measurement of the detector sensitivity. PMID:26686661

Recent advances in instrumentation have produced the first commercial examples of what can justifiably be called High Resolution ScanningElectron Microscopes. The key components of such instruments are a cold field emission gun, a small-gap immersion probe-forming lens, and a clean dry-pumped vacuum. The performance of these microscopes is characterized by several major features including a spatial resolution, in secondary electron mode on solid specimens, which can exceed 1nm on a routine basis; an incident probe current density of the order of 10{sup 6} amps/cm{sup 2}; and the ability to maintain these levels of performance over an accelerating voltage range of from 1 to 30keV. This combination of high resolution, high probe current, low contamination and flexible electron-optical conditions provides many new opportunitites for the application of the SEM to materials science, physics, and the life sciences. 27 refs., 14 figs.

Although many studies of the Golgi apparatus structure have been performed by light and electron microscopy, the full shape of the Golgi apparatus remained unclear due to the technical limitations of the previously applied microscopy techniques. In this study, we used serial section scanningelectron microscopy (SEM) for the morphological study of the Golgi apparatus. This method is useful for three-dimensional (3D) reconstruction of cellular structures without requiring specialized instruments, unlike focused ion beam SEM (FIB-SEM) and serial blockface SEM (SBF-SEM). Using the serial section SEM method developed by our laboratory, we investigate the 3D shape of the osmium-impregnated Golgi apparatus in rat epididymal cells, pancreatic acinar cells and gonadotropes. The combination of serial section SEM and a 3D reconstruction technique enabled us to elucidate the entire shape of the Golgi apparatus in these cells. The full shape of the Golgi apparatus in epididymal cells formed a basket-like structure with oval-shaped cisterns, while the Golgi apparatus in an acinar cell from the pancreas was composed of elongated ribbon-like structures that were connected to each other, making a coarse network. The overall image of the Golgi apparatus cisterns from a gonadotrope looked like a spherical cage. This study has clearly shown that entire 3D shape of the Golgi apparatus varies depending on the cell type and that the Golgi cisterns network appears as a single mass located in the large region of the cytoplasm. PMID:26609075

Electron-boson interactions are ubiquitous in systems ranging from simple metals to novel materials such as graphene, high-temperature superconductors and topological insulators. Of particular interest is the coupling between electrons and phonons. In general, electron-phonon coupling gives rise to quasiparticles of decreased mobility and increased effective mass. Nearly all information about electron-phonon coupling is contained in the Eliashberg function (α2 F (ω k , E)) of the material. In this talk I discuss the various methods by which the effects of electron-phonon coupling can be measured by scanning tunneling microscopy. I will present STM data on a variety of systems ranging from metals to topological insulators and discuss the signatures of electron-phonon interactions in different types of STM data. In particular I discuss how high resolution measurements allow us to measure the dispersion and obtain the real part of the self-energy, which can in principle be inverted to obtain the Eliashberg function.

Two fully aged amalgam alloys were examined using a scanning transmission electron microscope both in the transmission and scanning mode. The dispersed type amalgam containing a distribution of silver-copper spheres in addition to the Ag3Sn powder showed a markedly reduced gamma 1 grain size compared to a conventional Ag3Sn type amalgam. It is suggested that the increased compressive creep strength of the dispersed type material is a direct result of the reduced gamma 1 grain size and not due to a dispersion hardening effect from the cores of the remaining Ag-Cu spheres. Similarly, the formation of complex Cu-Sn intermediate phases at the Ag-Cu sphere surfaces are unlikely to lead to a dispersion strengthening effect. It is postulated that the reduced grain size in high copper amalgams is a consequence of the enhanced nucleating effect of a copper based phase on gamma 1. PMID:6640049

An electronicscanning pressure system that includes a plurality of pressure transducers is examined. A means obtains an electrical signal indicative of a pressure measurement from each of the plurality of pressure transducers. A multiplexing means is connected for selectivity supplying inputs from the plurality of pressure transducers to the signal obtaining means. A data bus connects the plurality of pressure transducers to the multiplexing means. A latch circuit is connected to supply control inputs to the multiplexing means. An address bus is connected to supply an address signal of a selected one of the plurality of pressure transducers to the latch circuit. In operation, each of the pressure transducers is successively scanned by the multiplexing means in response to address signals supplied on the address bus to the latch circuit.

Two screws and two washers, several small chips of tubing, and a fiber removed from a third screw were examined with the scanningelectron microscope and the electron microprobe. The purpose of the examination was to determine the nature of the material on the surface of these samples and to search for the presence of meteoritic material.

We demonstrate a new approach to characterize the frequency range in general scanningelectron microscope (SEM) images. First, pure frequency images are generated from low frequency to high frequency, and then, the magnification of each type of frequency image is implemented. By comparing the edge percentage of the SEM image to the self-generated frequency images, we can define the frequency ranges of the SEM images. Characterization of frequency ranges of SEM images benefits further processing and analysis of those SEM images, such as in noise filtering and contrast enhancement.

Frequency response was measured for different lengths and diameters of tubing between a sinusoidal pressure source and a pressure sensing module from an electronicallyscanned pressure measuring system. Measurements were made for straight runs of both steel and vinyl tubing. For steel tubing, measured results are compared with results calculated by using equations developed by Tijdeman and Bergh. Measurements were also made with a bend in the vinyl tubing at the module. In addition, measurements were made with two coils placed in the tubing near the middle of the run.

A prototype controller for the ESTAR (electronicallyscanned thinned array radiometer) instrument has been designed and tested. It manages the operation of the digital data subsystem (DDS) and its communication with the Small Explorer data system (SEDS). Among the data processing tasks that it coordinates are FEM data acquisition, noise removal, phase alignment and correlation. Its control functions include instrument calibration and testing of two critical subsystems, the output data formatter and Walsh function generator. It is implemented in a Xilinx XC3064PC84-100 field programmable gate array (FPGA) and has a maximum clocking frequency of 10 MHz.

Noise on scanningelectron microscope (SEM) images is studied. Gaussian noise is the most common type of noise in SEM image. We developed a new noise reduction filter based on the Wiener filter. We compared the performance of this new filter namely adaptive noise Wiener (ANW) filter, with four common existing filters as well as average filter, median filter, Gaussian smoothing filter and the Wiener filter. Based on the experiments results the proposed new filter has better performance on different noise variance comparing to the other existing noise removal filters in the experiments. PMID:26235517

This study aimed to examine the surface characteristics of erosive enamel in extracted human teeth by scanningelectron microscopy. Morphologic changes in naturally eroded enamel depend on the stages of dental erosion. In its early stages, the enamel surfaces show a honeycomb appearance due to the dissolution of enamel rod ends. In its advanced stages, the erosive process involves the underlying dentin and the eroded dentin shows exposed dentinal tubules and the dentinal matrix may be exposed due to the dissolution of the peri- and intertubular dentin. Evidence of remineralization is seen at the early stage of natural dental erosion. PMID:26214120

The scanningelectron microscope adds a new dimension to the knowledge that can be obtained from a failed microcircuit. When used with conventional techniques, SEM assists and clarifies the analysis, but it does not replace light microscopy. The most advantageous features for microcircuit analysis are long working distances and great depth of field. Manufacturer related failure modes of microcircuits are metallization defects, poor bonding, surface and particle contamination, and design and fabrication faults. User related failure modes are caused by abuse, such as overstress. The Physics of Failure Procedure followed by the Astrionics Laboratory in failure analysis is described, which is designed to obtain maximum information available from each step.

The three-dimensional reconstruction of a microscopic specimen has been obtained by applying the tomographic algorithm to a set of images acquired in a ScanningElectron Microscope. This result was achieved starting from a series of projections obtained by stepwise rotating the sample under the beam raster. The ScanningElectron Microscope was operated in the scanning-transmission imaging mode, where the intensity of the transmitted electron beam is a monotonic function of the local mass-density and thickness of the specimen. The detection strategy has been implemented and tailored in order to maintain the projection requirement over the large tilt range, as required by the tomographic workflow. A Si-based electron detector and an eucentric-rotation specimen holder have been specifically developed for the purpose.

Coupling the development of emerging experimental techniques in STEM and EELS with a fundamental understanding of atomic electronic structure afforded by DFT represents the unique approach and intention of this thesis. Scanning transmission electron microscopes equipped with high-angle annular dark field (HAADF) detectors and Gatan image filters (GIF) provide images and spectra, where the image brightness is interpreted as a function of atomic mass and thickness, and elemental specific spectra provide a means for the exploration of electronic and chemical structure of materials at the angstrom size scale. Over the past 20 years, the application of EELS in STEM has enabled more accurate elemental identification and exploration of electronic and chemical structure on angstrom-length scales, and arguably has provided an unprecedented wealth of materials characterization compared to other available techniques. Many materials issues related to specific novel properties that cannot be analyzed using the traditional techniques of the past, however, still remain unanswered. These concepts require a married approach of experiment and theory to fully explain. The intent of this dissertation is the development of improved analysis techniques that derive quantitative atomic scale information in connection with unraveling the origins of materials properties linked to the electronic structure and chemistry of materials.

A sample-heating system for spin-polarized scanningelectron microscopy (spin SEM) has been developed and used for microscopic magnetization analysis at temperatures up to 500°C. In this system, a compact ceramic heater and a preheating operation keep the ultra-high vacuum conditions while the sample is heated during spin SEM measurement. Moreover, the secondary-electron collector, which is arranged close to the sample, was modified so that it is not damaged at high temperatures. The system was used to heat a Co(1000) single-crystal sample from room temperature up to 500°C, and the magnetic-domain structures were observed. Changes of the domain structures were observed around 220 and 400°C, and these changes are considered to be due to phase transitions of this sample. PMID:23349241

We theoretically present the results for a scanning tunneling transport between a metallic tip and a Kondo lattice. We calculate the density of states (DOS) and the tunneling current and differential conductance (DC) under different conduction-fermion band hybridization and temperature in the Kondo lattice. It is found that the hybridization strength and temperature give asymmetric coherent peaks in the DOS separated by the Fermi energy. The corresponding current and DC intensity depend on the temperature and quantum interference effect among the c-electron and f-electron states in the Kondo lattice. Supported by the National Natural Science Foundation of China under Grant No. 11547203, and the Research Project of Education Department in Sichuan Province of China under Grant No. 15ZB0457

Scanningelectron microscopy (SEM) has been almost universally applied for the surface examination and characterization of both natural and man-made objects. Although an invasive technique, developments in electron microscopy over the years has given the microscopist a much clearer choice in how invasive the technique will be. With the advent of low vacuum SEM in the 1970s (The environmental cold stage, 1970) and environmental SEM in the late 1980s (J Microsc 160(pt. 1):9-19, 1989), it is now possible in some circumstances to examine samples without preparation. However, for the examination of biological tissue and cells it is still advisable to chemically fix, dehydrate, and coat samples for SEM imaging and analysis. This chapter aims to provide an overview of SEM as an imaging tool, and a general introduction to some of the methods applied for the preparation of samples. PMID:22907399

In this study, a combined tilt- and focal series is proposed as a new recording scheme for high-angle annular dark-field scanning transmission electron microscopy (STEM) tomography. Three-dimensional (3D) data were acquired by mechanically tilting the specimen, and recording a through-focal series at each tilt direction. The sample was a whole-mount macrophage cell with embedded gold nanoparticles. The tilt focal algebraic reconstruction technique (TF-ART) is introduced as a new algorithm to reconstruct tomograms from such combined tilt- and focal series. The feasibility of TF-ART was demonstrated by 3D reconstruction of the experimental 3D data. The results were compared with a conventional STEM tilt series of a similar sample. The combined tilt- and focal series led to smaller missing wedge artifacts, and a higher axial resolution than obtained for the STEM tilt series, thus improving on one of the main issues of tilt series-based electron tomography.

In this paper, we evaluate and compare doping contrast generated inside the scanningelectron microscope (SEM) and scanning helium ion microscope (SHIM). Specialised energy-filtering techniques are often required to produce strong doping contrast to map donor distributions using the secondary electron (SE) signal in the SEM. However, strong doping contrast can be obtained from n-type regions in the SHIM, even without energy-filtering. This SHIM technique is more sensitive than the SEM to donor density changes above its sensitivity threshold, i.e. of the order of 10(16) or 10(17)donorscm(-3) respectively on specimens with or without a p-n junction; its sensitivity limit is well above 2×10(17)acceptorscm(-3) on specimens with or without a p-n junction. Good correlation is found between the widths and slopes of experimentally measured doping contrast profiles of thin p-layers and the calculated widths and slopes of the potential energy distributions across these layers, at a depth of 1 to 3nm and 5 to 10nm below the surface in the SHIM and the SEM respectively. This is consistent with the mean escape depth of SEs in silicon being about 1.8nm and 7nm in the SHIM and SEM respectively, and we conclude that short escape depth, low energy SE signals are most suitable for donor profiling. PMID:26624515

Highlights: • Bioaerosols were captured using the filter method. • Bioaerosols were analysed using scanningelectron microscope. • Bioaerosols were classified on the basis of morphology. • Single small cells were found more frequently than aggregates and larger cells. • Smaller cells may disperse further than heavier aggregate structures. - Abstract: This research classifies the physical morphology (form and structure) of bioaerosols emitted from open windrow composting. Aggregation state, shape and size of the particles captured are reported alongside the implications for bioaerosol dispersal after release. Bioaerosol sampling took place at a composting facility using personal air filter samplers. Samples were analysed using scanningelectron microscopy. Particles were released mainly as small (<1 μm) single, spherical cells, followed by larger (>1 μm) single cells, with aggregates occurring in smaller proportions. Most aggregates consisted of clusters of 2–3 particles as opposed to chains, and were <10 μm in size. No cells were attached to soil debris or wood particles. These small single cells or small aggregates are more likely to disperse further downwind from source, and cell viability may be reduced due to increased exposure to environmental factors.

Correlative light and electron microscopy (CLEM) is a unique method for investigating biological structure-function relations. With CLEM protein distributions visualized in fluorescence can be mapped onto the cellular ultrastructure measured with electron microscopy. Widespread application of correlative microscopy is hampered by elaborate experimental procedures related foremost to retrieving regions of interest in both modalities and/or compromises in integrated approaches. We present a novel approach to correlative microscopy, in which a high numerical aperture epi-fluorescence microscope and a scanningelectron microscope illuminate the same area of a sample at the same time. This removes the need for retrieval of regions of interest leading to a drastic reduction of inspection times and the possibility for quantitative investigations of large areas and datasets with correlative microscopy. We demonstrate Simultaneous CLEM (SCLEM) analyzing cell-cell connections and membrane protrusions in whole uncoated colon adenocarcinoma cell line cells stained for actin and cortactin with AlexaFluor488. SCLEM imaging of coverglass-mounted tissue sections with both electron-dense and fluorescence staining is also shown. PMID:23409024

An initial study using electron beam induced current (EBIC) to evaluate solar cells has been carried out with the large chamber scanningelectron microscope (LC-SEM) at the Western Kentucky University Nondestructive Analysis Center. EBIC is a scanningelectron microscope technique used for the characterization of semiconductors. To facilitate our studies, we developed a Solar Amplification System (SASY) for analyzing current distribution and defects within a solar cell module. Preliminary qualitative results will be shown for a solar cell module that demonstrates the viability of the technique using the LC-SEM. Quantitative EBIC experiments will be carried out to analyze defects and minority carrier properties. Additionally, a well-focused spot of light from an LED mounted at the side of the SEM column will scan the same area of the solar cell using the LC-SEM positioning system. SASY will then output the solar efficiency to be compared with the minority carrier properties found using EBIC.

A surface analysis system has been newly developed with combination of ultrahigh vacuum scanningelectron microscope (SEM) and wide-movable scanning tunneling microscope (STM). The basic performance is experimentally demonstrated. These SEM and STM images are clear enough to obtain details of surface structures. The STM unit moves horizontally over several millimeters by sliding motion of PZT actuators. The motion resolution is proved to be submicrometers. The STM tip mounted on another PZT scanner can be guided to a specific object on the sample surface during SEM observation. In the observation of a Si(111) surface rapidly cooled from high temperature, the STM tip was accurately guided to an isolated atomic step and slightly moved along it during SEM observation. The STM observation shows an asymmetry of the (7x7)-transformed region along the step between the upper and lower terraces. (7x7) bands continuously formed along the edge of terraces, while (7x7) domains distributed on the terraces slightly far from the step. These experiments show the wide-movable STM unit resolves a gap of observation area between SEM and STM and the system enables a specific object found in the SEM image to be observed easily by STM.

Ballistic propagation and the light-like dispersion of graphene charge carriers make graphene an attractive platform for optics-inspired graphene electronics where gate tunable potentials can control electron refraction and transmission. In analogy to optical wave propagation in lenses, mirrors and metamaterials, gate potentials can be used to create a negative index of refraction for Veselago lensing and Fabry-Pérot interferometers. In circular geometries, gate potentials can induce whispering gallery modes (WGM), similar to optical and acoustic whispering galleries albeit on a much smaller length scale. Klein scattering of Dirac carriers plays a central role in determining the coherent propagation of electron waves in these resonators. In this talk, I examine the probing of electron resonators in graphene confined by linear and circular gate potentials with the scanning tunneling microscope (STM). The tip in the STM tunnel junction serves both as a tunable local gate potential, and as a probe of the graphene states through tunneling spectroscopy. A combination of a back gate potential, Vg, and tip potential, Vb, creates and controls a circular pn junction that confines the WGM graphene states. The resonances are observed in two separate channels in the tunneling spectroscopy experiment: first, by directly tunneling into the state at the bias energy eVb, and, second, by tunneling from the resonance at the Fermi level as the state is gated by the tip potential. The second channel produces a fan-like set of WGM peaks, reminiscent of the fringes seen in planar geometries by transport measurements. The WGM resonances split in a small applied magnetic field, with a large energy splitting approaching the WGM spacing at 0.5 T. These results agree well with recent theory on Klein scattering in graphene electron resonators. This work is done in collaboration with Y. Zhao, J. Wyrick, F.D. Natterer, J. F. Rodriquez-Nieva, C. Lewandoswski, K. Watanabe, T. Taniguchi, N. B

This paper presents a high-resolution transmittance electron energy analyzer suitable for use as an attachment inside the specimen chambers of scanningelectron/ion microscopes. The analyzer uses a rotationally symmetric electric field distribution to transport electrons/ions emitted from a central point source in a radial direction on to a ring-shaped collection/detection area. The analyzer is designed to fit around a conical shaped objective lens pole-piece/electrode, allowing for a relatively short minimum working distance, 5 mm or less. Simulation results for the analyzer design predict that it will have a relative energy resolution of 0.025% for an entrance angular spread of ±6°, around an order of magnitude better then the well-known Cylindrical Mirror Analyzer (CMA). The analyzer design allows for a parallel mode of operation in which the energy bandwidth on a conical shaped detection plane is predicted to be as high as 32% (±16%) of the central-band energy. On a flat ring-shaped detection plane, the energy bandwidth is predicted to be around 12% (±6%) of the central-band energy, over which the simulated relative energy resolution remains below 0.06% for angular spreads of ±6°.

A three-dimensional (3D) reconstruction of the cytoskeleton and a clathrin-coated pit in mammalian cells has been achieved from a focal-series of images recorded in an aberration-corrected scanning transmission electron microscope (STEM). The specimen was a metallic replica of the biological structure comprising Pt nanoparticles 2–3 nm in diameter, with a high stability under electron beam radiation. The 3D dataset was processed by an automated deconvolution procedure. The lateral resolution was 1.1 nm, set by pixel size. Particles differing by only 10 nm in vertical position were identified as separate objects with greater than 20% dip in contrast between them. We refer to this value as the axial resolution of the deconvolution or reconstruction, the ability to recognize two objects, which were unresolved in the original dataset. The resolution of the reconstruction is comparable to that achieved by tilt-series transmission electron microscopy. However, the focal-series method does not require mechanical tilting and is therefore much faster. 3D STEM images were also recorded of the Golgi ribbon in conventional thin sections containing 3T3 cells with a comparable axial resolution in the deconvolved dataset. PMID:20082729

Environmental colloids are toxic or radioactive particles suspended in ground or surface water. These hazardous particles can facilitate and accelerate the transport of toxicants and enhance the threat to humans by exposure to pathogenic substances. The chemical and physical properties of hazardous colloids have not been well characterized nor are there standard colloid remediation technologies to prevent their deleterious effects. Colloid characterization requires measurement of their size distribution, zeta potential, chemical composition, adsorption capacity and morphology. The environmental scanningelectron microscope (ESEM) by ElectroScan, Inc., analyzes particle sizes, composition, and morphology. It is also used in this study to identify the attachment of colloids onto packing or rock surfaces in the development of a colloid remediation process. The ESEM has confirmed the composition of groundwater colloids in these studies to be generally the same material as the surrounding rock. The morphology studies have generally shown that colloids are simply small pieces of the rock surface that have exfoliated into the surrounding water. However, in general, the source and chemical composition of groundwater colloids is site dependent. The authors have found that an ESEM works best as a valuable analysis tool within a suite of colloid characterization instruments.

Scanningelectron microscope improves the possibility of investigation of surroundings near of gunshot wounds in forensic medicine, it is the next subsequent method for differentiating of area of entrance and exit wound, supplemental method for determination of firing distance, permit of detection (GSR) on the hand of shooter and ensured describing of samples and their stored. Detection of GSR provides many information about composition of bullet and primer. Authors are demonstrating the possibility of detection of GSR on experimental shooting to the krupon (pigs' skin) in different situation (such as in a room and in outside area) and using of different weapon (hand gun CZ No.75 and machine gun No.58). PMID:16948447

Undecalcified samples extracted from human femoral shafts are fractured by bending and the fracture surfaces are examined with a scanningelectron microscope (SEM). The investigation is performed on both dry and wet (hydrated with a saline solution) specimens. SEM micrographs show patterns in many respects similar to those observed in fractography studies of laminated fiber-reinforced synthetic composites. In particular, dry and wet samples behave like brittle and ductile matrix laminates, respectively. An analysis carried out on the basis of the mechanisms that dominate the fracture process of laminates shows that a reasonable cortical bone model is that of a laminated composite material whose matrix is composed of extracellular noncollagenous calcified proteins, and the reinforcement is constituted by the calcified collagen fiber system. PMID:9001936

Scanningelectron microscopy (SEM) of Purkinje fibres (P-fibres) from the septal walls and the septomarginal trabecula was performed on deparaffinized sections, the identification in SEM made possible by comparative light microscopy. The myofibrils in P-fibres from the septal walls were arranged in a cart-wheel fashion, whereas P-fibres from the septomarginal trabecula showed a nearly parallel alignment of the contractile material. Z-line ridges resembling the T-tubules of the myocardial fibres were observed in both kinds of P-fibres. The myofibrillar arrangements are discussed in relation to the expected mechanical stress put upon P-fibres in the 2 locations during systolic-diastolic activity. An adaptive function of the contractile material to the mechanical stress is suggested and the possible need of a T-tubular system is discussed. PMID:507370

A 39-year-old female with a large cavernous hemangioma of the liver was successfully treated by ligation of the left hepatic artery. A wedge biopsy specimen of the hemangioma was obtained after the ligation and was examined by scanningelectron microscopy. The hemangioma was demarcated from the surrounding normal liver parenchyma and had a labyrinth of caves 50-150 microns in diameter. The caves were separated by fibrous septa 20-40 microns in width. Endothelial cells of the caves were spindle-shaped and arranged in parallel. The surface property of the caves resembled that of the hepatic artery and differed from that of the portal vein or hepatic vein. These findings support that the cavernous hemangioma of the liver was supplied by the hepatic artery. The labyrinthine structure of the cavernous hemangioma may explain the long standing contrast enhancement of the hemangioma after hepatic arteriography. PMID:6832546

Meteorites provide a wealth of information about the solar system's formation, since they have similar building blocks as the Earth's crust but have been virtually unaltered since their formation. Some stony meteorites contain minerals and silicate inclusions, called chondrules, in the matrix. Utilizing Moessbauer spectroscopy, we identified minerals in the Murchison meteorite, a carbonaceous chondritic meteorite, by the gamma ray resonance lines observed. Absorption patterns of the spectra were found due to the minerals olivine and phyllosilicate. We used a scanningelectron microscope to describe the structure of the chondrules in the Murchison meteorite. The chondrules were found to be deformed due to weathering of the meteorite. Diameters varied in size from 0.2 to 0.5 mm. Further enhancement of the microscopic imagery using a digital image processor was used to describe the physical characteristics of the inclusions.

To investigate the existence of subspecies of Anopheles albimanus Wiedeman in southern Mexico, the egg morphology of specimens obtained from several field populations and from insectary-adapted colonies of uniform pupal phenotype was examined. Scanningelectron microscopic observations have shown that the eggs of An. albimanus are polymorphic in respect to the size and shape of their floats, but not in their ornamentation. Four types of eggs were found. Differences in the proportion of the various morphological types were statistically significant, although proportions of egg types were variable among individuals within the same population. These observations are suggestive of distinctive populations and warrant further studies using more sensitive methods to investigate sibling species in An. albimanus sensu lato. PMID:1625289

Retinal lesions are described with the scanningelectron microscope in the uveo retinitis induced in guinea pigs by immunization with rod outer segments of bovine retina. The two surfaces in contact of the pigment epithelium and the photoreceptors are separated from each other and observed on flat preparations. On the epithelial side, the evolution of the degenerescence of epithelial cells is observed, from the early disappearance of villosities until the total destruction of the cells. Through lacks in the epithelial layer where the choroid appears, inflammatory cells migrate towards the retina. The impairement of the visual cells is characterized by progressive destruction of outer then inner segments, with preservation of the external limiting membrane. In some areas the degenerative process reaches the layer of visual cells nuclei. Macrophages, and local clusters of lymphocytes are seen in contact with the retinal surface. PMID:135548

Ultrastructural analysis of cells can reveal valuable information about their morphological, physiological, and biochemical characteristics. Scanningelectron microscopy (SEM) has been widely used to provide high-resolution images from the surface of biological samples. However, samples need to be dehydrated and coated with conductive materials for SEM imaging. Besides, immobilizing non-adherent cells during processing and analysis is challenging and requires complex fixation protocols. In this work, we developed a novel dielectrophoresis based microfluidic platform for interfacing non-adherent cells with high-resolution SEM at low vacuum mode. The system enables rapid immobilization and dehydration of samples without deposition of chemical residues over the cell surface. Moreover, it enables the on-chip chemical stimulation and fixation of immobilized cells with minimum dislodgement. These advantages were demonstrated for comparing the morphological changes of non-budding and budding yeast cells following Lyticase treatment. PMID:25089528

The external ultrastructure of the anterior and posterior extremities of the nematodes, Strongylus asini , Strongylus vulgaris, Strongylus equinus and Strongylus edentatus, was studied with scanningelectron microscopy (SEM). Fresh specimens of S. asini were collected from the caecum, ventral colon and vena portae of Equus burchelli and Equus zebra hartmannae ; S. vulgaris from the caecum, colon and arteria ileocolica of E. burchelli ; S. equinus from the ventral colon of E. z. hartmannae and S. edentatus from the caecum and ventral colon of both zebras , during surveys of parasites in zebras in the Etosha Game Reserve, South West Africa/Namibia, and the Kruger National Park, Republic of South Africa. The worms were cleaned, fixed and mounted by standard methods and photographed in a JEOL JSM - 35C scanningelectron microscope (SEM) operating at 12kV . The SEM showed the following differences: the tips of the external leaf-crowns varied and were fine and delicate in S. asini , coarse and broad in S. vulgaris and, in S. equinus and S. edentatus, closely adherent, separating into single elements for half their length. The excretory pores showed only slight variation, and the morphology of the copulatory bursae did not differ from those seen with light microscopy. The genital cones differed markedly: S. asini had a ventral triangular projection and laterally 2 finger-like projections: in S. vulgaris there were numerous bosses on the lateral and ventral aspects of the cone; in S. equinus 2 finger-like processes projected laterocaudally ; and in S. edentatus 2 pairs of papilla-like processes projected laterally on the ventral aspects, and a pair of rounded projections and a pair of hair-like structures adorned the dorsal aspects.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6676687

Amyloid fibrils are filamentous protein aggregates implicated in several common diseases such as Alzheimer's disease and type II diabetes. Similar structures are also the molecular principle of the infectious spongiform encephalopathies such as Creutzfeldt-Jakob disease in humans, scrapie in sheep, and of the so-called yeast prions, inherited non-chromosomal elements found in yeast and fungi. Scanning transmission electron microscopy (STEM) is often used to delineate the assembly mechanism and structural properties of amyloid aggregates. In this review we consider specifically contributions and limitations of STEM for the investigation of amyloid assembly pathways, fibril polymorphisms and structural models of amyloid fibrils. This type of microscopy provides the only method to directly measure the mass-per-length (MPL) of individual filaments. Made on both in vitro assembled and ex vivo samples, STEM mass measurements have illuminated the hierarchical relationships between amyloid fibrils and revealed that polymorphic fibrils and various globular oligomers can assemble simultaneously from a single polypeptide. The MPLs also impose strong constraints on possible packing schemes, assisting in molecular model building when combined with high-resolution methods like solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR).

Electron tomography in materials science has flourished with the demand to characterize nanoscale materials in three dimensions (3D). Access to experimental data is vital for developing and validating reconstruction methods that improve resolution and reduce radiation dose requirements. This work presents five high-quality scanning transmission electron microscope (STEM) tomography datasets in order to address the critical need for open access data in this field. The datasets represent the current limits of experimental technique, are of high quality, and contain materials with structural complexity. Included are tomographic series of a hyperbranched Co2P nanocrystal, platinum nanoparticles on a carbon nanofibre imaged over the complete 180° tilt range, a platinum nanoparticle and a tungsten needle both imaged at atomic resolution by equal slope tomography, and a through-focal tilt series of PtCu nanoparticles. A volumetric reconstruction from every dataset is provided for comparison and development of post-processing and visualization techniques. Researchers interested in creating novel data processing and reconstruction algorithms will now have access to state of the art experimental test data. PMID:27272459

Electron tomography in materials science has flourished with the demand to characterize nanoscale materials in three dimensions (3D). Access to experimental data is vital for developing and validating reconstruction methods that improve resolution and reduce radiation dose requirements. This work presents five high-quality scanning transmission electron microscope (STEM) tomography datasets in order to address the critical need for open access data in this field. The datasets represent the current limits of experimental technique, are of high quality, and contain materials with structural complexity. Included are tomographic series of a hyperbranched Co2P nanocrystal, platinum nanoparticles on a carbon nanofibre imaged over the complete 180° tilt range, a platinum nanoparticle and a tungsten needle both imaged at atomic resolution by equal slope tomography, and a through-focal tilt series of PtCu nanoparticles. A volumetric reconstruction from every dataset is provided for comparison and development of post-processing and visualization techniques. Researchers interested in creating novel data processing and reconstruction algorithms will now have access to state of the art experimental test data. PMID:27272459

This paper reviews the development of molecular tips for scanning tunneling microscopy (STM). Molecular tips offer many advantages: first is their ability to perform chemically selective imaging because of chemical interactions between the sample and the molecular tip, thus improving a major drawback of conventional STM. Rational design of the molecular tip allows sophisticated chemical recognition; e.g., chiral recognition and selective visualization of atomic defects in carbon nanotubes. Another advantage is that they provide a unique method to quantify electron transfer between single molecules. Understanding such electron transfer is mandatory for the realization of molecular electronics. PMID:24420248

Samples of postmortem pink teeth were investigated by scanningelectron microscopy and electron probe X-ray microanalysis. Fracture surfaces of the dentin in pink teeth were noticeably rough and revealed many more smaller dentinal tubules than those of the control white teeth. Electron probe X-ray microanalysis showed that the pink teeth contained iron which seemed to be derived from blood hemoglobin. The present study confirms that under the same circumstance red coloration of teeth may occur more easily in the teeth in which the dentin is less compact and contains more dentinal tubules.

SCAN+ is a software application specifically designed to control the positioning of a gamma spectrometer by a two dimensional translation system above spent fuel bundles located in a sealed spent fuel cask. The gamma spectrometer collects gamma spectrum information for the purpose of spent fuel cask fuel loading verification. SCAN+ performs manual and automatic gamma spectrometer positioning functions as-well-as exercising control of the gamma spectrometer data acquisitioning functions. Cask configuration files are used to determine the positions of spent fuel bundles. Cask scanning files are used to determine the desired scan paths for scanning a spent fuel cask allowing for automatic unattended cask scanning that may take several hours.

Heterogeneous ice nucleation is one of the processes of critical relevance to a range of topics in the fundamental and the applied science and technologies. Heterogeneous ice nucleation initiated by particles proceeds where microscopic properties of particle surfaces essentially control nucleation mechanisms. Ice nucleation in the atmosphere on particles governs the formation of ice and mixed phase clouds, which in turn influence the Earth's radiative budget and climate. Heterogeneous ice nucleation is still insufficiently understood and poses significant challenges in predictive understanding of climate change. We present a novel microscopy platform allowing observation of individual ice nucleation events at temperature range of 193-273 K and relative humidity relevant for ice formation in the atmospheric clouds. The approach utilizes a home built novel ice nucleation cell interfaced with Environmental ScanningElectron Microscope (IN-ESEM system). The IN-ESEM system is applied for direct observation of individual ice formation events, determining ice nucleation mechanisms, freezing temperatures, and relative humidity onsets. Reported microanalysis of the ice nucleating particles (INP) include elemental composition detected by the energy dispersed analysis of X-rays (EDX), and advanced speciation of the organic content in particles using scanning transmission x-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). The performance of the IN-ESEM system is validated through a set of experiments with kaolinite particles with known ice nucleation propensity. We demonstrate an application of the IN-ESEM system to identify and characterize individual INP within a complex mixture of ambient particles.

A high-speed direct electron detection system is introduced to the field of transmission electron microscopy and applied to strain measurements in semiconductor nanostructures. In particular, a focused electron probe with a diameter of 0.5 nm was scanned over a fourfold quantum layer stack with alternating compressive and tensile strain and diffracted discs have been recorded on a scintillator-free direct electron detector with a frame time of 1 ms. We show that the applied algorithms can accurately detect Bragg beam positions despite a significant point spread each 300 kV electron causes during detection on the scintillator-free camera. For millisecond exposures, we find that strain can be measured with a precision of 1.3 Multiplication-Sign 10{sup -3}, enabling, e.g., strain mapping in a 100 Multiplication-Sign 100 nm{sup 2} region with 0.5 nm resolution in 40 s.

A new design of secondary electron (SE) detector is described for use in low-vacuum scanningelectron microscopes. Its distinguishing feature is a separate detector chamber, which can be maintained at a pressure independent of the pressure in the specimen chamber. The two chambers are separated by a perforated membrane or mesh across which an electric field is applied, making it relatively transparent to low-energy electrons but considerably less so to the gas molecules. The benefits of this arrangement are discussed. The final means of detecting the electrons can be a conventional scintillator and photomultiplier arrangement or any of the methods using the ambient gas as an amplifying medium. Images obtained with the detector show good SE contrast and low backscattered electron contribution. PMID:14748387

Pores are naturally occurring entities in bone. Changes in pore size and number are often associated with diseases such as Osteoporosis and even microgravity during spaceflight. Studying bone perforations may yield great insight into bone's material properties, including bone density and may contribute to identifying therapies to halt or potentially reverse bone loss. Current technologies used in this field include nuclear magnetic resonance, micro-computed tomography and the field emission scanningelectron microscope (FE-SEM) 2, 5. However, limitations in each method limit further advancement. The objective of this study was to assess the effectiveness of using a new generation of analytical instruments, the TM-1000 tabletop, SEM with back-scatter electron (BSE) detector, to analyze cortical bone porosities. Hind limb unloaded and age-based controlled mouse femurs were extracted and tested in vitro for changes in pores on the periosteal surface. An important advantage of using the tabletop is the simplified sample preparation that excludes extra coatings, dehydration and fixation steps that are otherwise required for conventional SEM. For quantitative data, pores were treated as particles in order to use an analyze particles feature in the NIH ImageJ software. Several image-processing techniques for background smoothing, thresholding and filtering were employed to produce a binary image suitable for particle analysis. It was hypothesized that the unloaded bones would show an increase in pore area, as the lack of mechanical loading would affect bone-remodeling processes taking place in and around pores. Preliminary results suggest only a slight different in frequency but not in size of pores between unloaded and control femurs.

Candida biofilms on indwelling devices are an increasing problem in patients treated at intensive care units. The goal of this study was to examine the occurrence and frequency of these biofilms. A total of 172 catheters were collected from 105 male and 67 female patients (the age range of both patient groups was from 3 weeks to 98 years old). The catheters were incubated on blood agar plates and the resulting yeast colonies were subsequently identified. Furthermore, pieces of catheters were fixed, dried and sputter coated with gold for investigation with scanningelectron microscopy (SEM). Yeasts were recovered from significantly more catheters obtained from men than from women (chi(2): n = 67; P < 0.01). In SEM, 56.4% catheters turned out to be positive for biofilm formation. Again catheters from male patients were statistically significant (chi(2): n = 40; P < 0.01) more often positive than those from women. Candida albicans (71.1%) was the most common species isolated from the catheters, followed by C. glabrata (10.3%), C. parapsilosis (8.2%) and C. tropicalis (5.2%). Based on the results of this investigation, the epidemiology of Candida biofilms on indwelling devices seems to be a promising target for future investigations. PMID:19888801

Non-thermal plasmas hold great promise for a variety of biomedical applications. To ensure safe clinical application of plasma, a rigorous analysis of plasma-induced effects on cell functions is required. Yet mechanisms of bacteria deactivation by non-thermal plasma remain largely unknown. We therefore analyzed the influence of low-temperature atmospheric plasma on Gram-positive and Gram-negative bacteria. Using scanningelectron microscopy, we demonstrate that both Gram-positive and Gram-negative bacteria strains in a minute were completely destroyed by helium plasma. In contrast, mesenchymal stem cells (MSCs) were not affected by the same treatment. Furthermore, histopathological analysis of hematoxylin and eosin-stained rat skin sections from plasma-treated animals did not reveal any abnormalities in comparison to control ones. We discuss possible physical mechanisms leading to the shred of bacteria under non-thermal plasma irradiation. Our findings disclose how helium plasma destroys bacteria and demonstrates the safe use of plasma treatment for MSCs and skin cells, highlighting the favorability of plasma applications for chronic wound therapy.

Segmentation and classification are prolific research topics in the image processing community. These topics have been increasingly used in the context of analysis of cementitious materials on images acquired with a scanningelectron microscope. Indeed, there is a need to be able to detect and to quantify the materials present in a cement paste in order to follow the chemical reactions occurring in the material even days after the solidification. We propose a new approach for segmentation and classification of cementitious materials based on the denoising of the data with a block-matching three-dimensional (3-D) algorithm, binary partition tree (BPT) segmentation, support vector machines (SVM) classification, and interactivity with the user. The BPT provides a hierarchical representation of the spatial regions of the data, allowing a segmentation to be selected among the admissible partitions of the image. SVMs are used to obtain a classification map of the image. This approach combines state-of-the-art image processing tools with user interactivity to allow a better segmentation to be performed, or to help the classifier discriminate the classes better. We show that the proposed approach outperforms a previous method when applied to synthetic data and several real datasets coming from cement samples, both qualitatively with visual examination and quantitatively with the comparison of experimental results with theoretical ones.

Non-thermal plasmas hold great promise for a variety of biomedical applications. To ensure safe clinical application of plasma, a rigorous analysis of plasma-induced effects on cell functions is required. Yet mechanisms of bacteria deactivation by non-thermal plasma remain largely unknown. We therefore analyzed the influence of low-temperature atmospheric plasma on Gram-positive and Gram-negative bacteria. Using scanningelectron microscopy, we demonstrate that both Gram-positive and Gram-negative bacteria strains in a minute were completely destroyed by helium plasma. In contrast, mesenchymal stem cells (MSCs) were not affected by the same treatment. Furthermore, histopathological analysis of hematoxylin and eosin–stained rat skin sections from plasma–treated animals did not reveal any abnormalities in comparison to control ones. We discuss possible physical mechanisms leading to the shred of bacteria under non-thermal plasma irradiation. Our findings disclose how helium plasma destroys bacteria and demonstrates the safe use of plasma treatment for MSCs and skin cells, highlighting the favorability of plasma applications for chronic wound therapy.

The demands which radar installations have to satisfy are rising with increasing traffic density in the case of civil applications and a growing threat level in the case of the military sector. In many instances, these demands can only be met by adapting the value of the transmitted power to the traffic density or the magnitude of the threat. Such an approach requires the employment of computer-aided radar systems with electronically-controlled antennas. The considered systems have currently also advantages with respect to reliability and cost effectiveness. The present investigation is concerned with suitable procedures for the improvement of the energy management, taking into account mainly aspects of radar control and signal processing. The discussion is based on the consideration of a planar array antenna. Differences arising in connection with the use of other types of antennas are also briefly examined. The employment of an immobile radar antenna for ground-based airspace observation is considered. Attention is given to the appropriate selection of the width of the lobe, the scanning, the tilt of the antenna, and antenna performance characteristics.

Scanningelectron microscopy was used to examine the major stages of the life cycle of two wild-type strains of Neurospora crassa Shear and Dodge (St. Lawrence 3.1a and 74A): mycelia, protoperithecium formation, perithecia, ascospores, ascospore germination and outgrowth, macro and microconidia, and germination and outgrowth of macroconidia. Structures seen at the limit of resolution of bright-field and phase-contrast microscopes, e.g., the ribbed surface of ascospores, are well resolved. New details of conidial development and surface structure are revealed. There appears to be only one distinguishable morphological difference between the two strains. The pattern of germination and outgrowth which seems relatively constant for strain 74A or strain 3.1a, appears to be different for each. Conidia from strain 3.1a almost always germinate from a site between interconidial attachment points; whereas the germ tubes of strain 74A usually emerge from or very near the interconidial attachment site. These germination patterns usually do not segregate 2:2 in asci dissected in order. This observation suggests that conidial germination pattern is not under the control of a single gene. Images PMID:4266170

PURPOSE Topographic analysis of treated ceramics provides qualitative information regarding the surface texture affecting the micromechanical retention and locking of resin-ceramics. This study aims to compare the surface microstructure following different surface treatments of feldspathic porcelain. MATERIALS AND METHODS This in-vitro study was conducted on 72 porcelain discs randomly divided into 12 groups (n=6). In 9 groups, feldspathic surfaces were subjected to sandblasting at 2, 3 or 4 bar pressure for 5, 10 or 15 seconds with 50 µm alumina particles at a 5 mm distance. In group 10, 9.5% hydrofluoric acid (HF) gel was applied for 120 seconds. In group 11, specimens were sandblasted at 3 bar pressure for 10 seconds and then conditioned with HF. In group 12, specimens were first treated with HF and then sandblasted at 3 bar pressure for 10 seconds. All specimens were then evaluated under scanningelectron microscopy (SEM) at different magnifications. RESULTS SEM images of HF treated specimens revealed deep porosities of variable sizes; whereas, the sandblasted surfaces were more homogenous and had sharper peaks. Increasing the pressure and duration of sandblasting increased the surface roughness. SEM images of the two combined techniques showed that in group 11 (sandblasted first), HF caused deeper porosities; whereas in group 12 (treated with HF first) sandblasting caused irregularities with less homogeneity. CONCLUSION All surface treatments increased the surface area and caused porous surfaces. In groups subjected to HF, the porosities were deeper than those in sandblasted only groups. PMID:25352961

Pulmonary aggregation of inhaled {sup 239}PuO{sub 2} particles leads to a cellular evolution of focal inflammation, fibrosis, epithelial dysplasia and lung tumor formation. Female Wistar rats were exposed to an aerosol of high-fired {sup 239}PuO{sub 2} (initial lung burden, 3.9 kBq) and the lungs examined at intervals from 1 day to 700 days after exposure by light and scanningelectron microscopy and autoradiography. Peribronchiolar Pu particle aggregation increased with time, resulting in well-defined focal inflammatory lesions after 120 days and fibrotic lesions after 180 days. A generalized hypertrophy and hyperplasia of nonciliated bronchiolar cells was seen at 15 days and type II cell hyperplasia by 30 days after exposure. Focal dysplastic changes in type II alveolar epithelium and terminal nonciliated bronchiolar epithelium preceded carcinoma formation. Alveolar bronchiolarization was first noted at 120 days, squamous metaplasia at 210 days, squamous carcinoma at 270 days and adenocarcinoma at 600 days after exposure.

The unique nature of vestibular otoconia as calcium carbonate biominerals makes them particularly susceptible to chemical deformation during histological processing. We fixed and stored otoconia from all three otolith endorgans of embryonic, hatchling and adult Japanese quail in glutaraldehyde containing either phosphate or non-phosphate buffers for varying lengths of time and processed them for scanningelectron microscopy. Otoconia from all age groups and otolith endorgans processed in 0.1 M phosphate buffer (pH 7.4) showed abnormal surface morphology when compared to acetone fixed controls. Otoconia processed in 0.1 M sodium cacodylate or HEPES buffered artificial endolymph (pH 7.4) showed normal morphology that was similar to controls. The degree of otoconial deformation was directly related to the time exposed to phosphate buffer. Short duration exposure produced particulate deformations while longer exposures resulted in fused otoconia that formed solid sheets. Otoconial surface deformation and fusing was independent of the glutaraldehyde component of the histological processing. These findings should help vestibular researchers to develop appropriate histological processing protocols in future studies of otoconia.

The bandwidth and contrast of secondary electron (SE) images obtained using variable pressure scanningelectron microscopy are enhanced when a grounded Frisch grid is placed between the SE detecting anode and the negatively biased stage. The improvement in SE image quality occurs as a consequence of the grounded Frisch grid electrostatically screening the 'slow' induced ion current signal, generated below the grid, from the induced current detected above the grid by the anode. Ion induced artefacts, such as image smearing at fast scan rates, are virtually eliminated using a Frisch grid. Gas amplification data are presented to illustrate that gas gain can be optimized by varying the Frisch grid-stage (amplification region) separation Frisch grid-anode (drift region) separation and stage bias.

In this paper, we investigate the tendency of porous low-K dielectrics (also named Ultra Low-K, ULK) behavior to shrink when exposed to the electron beam of a scanningelectron microscope. Various experimental electron beam conditions have been used for irradiating ULK thin films, and the resulting shrinkage has been measured through use of an atomic force microscope tool. We report the shrinkage to be a fast, cumulative, and dose dependent effect. Correlation of the shrinkage with incident electron beam energy loss has also been evidenced. The chemical modification of the ULK films within the interaction volume has been demonstrated, with a densification of the layer and a loss of carbon and hydrogen elements being observed.

Recent progress in nanotechnology enables the production of atomically abrupt interfaces in multilayered junctions, allowing for an increase in the number of transistors in a processor. However, uniform electron transport has not yet been achieved across the entire interfacial area in junctions due to the existence of local defects, causing local heating and reduction in transport efficiency. To date, junction uniformity has been predominantly assessed by cross-sectional transmission electron microscopy, which requires slicing and milling processes that can potentially introduce additional damage and deformation. It is therefore essential to develop an alternative non-destructive method. Here we show a non-destructive technique using scanningelectron microscopy to map buried junction properties. By controlling the electron-beam energy, we demonstrate the contrast imaging of local junction resistances at a controlled depth. This technique can be applied to any buried junctions, from conventional semiconductor and metal devices to organic devices. PMID:27586090

SCAN+ is a software application specifically designed to control the positioning of a gamma spectrometer by a two dimensional translation system above spent fuel bundles located in a sealed spent fuel cask. The gamma spectrometer collects gamma spectrum information for the purpose of spent fuel cask fuel loading verification. SCAN+ performs manual and automatic gamma spectrometer positioning functions as-well-as exercising control of the gamma spectrometer data acquisitioning functions. Cask configuration files are used to determinemore » the positions of spent fuel bundles. Cask scanning files are used to determine the desired scan paths for scanning a spent fuel cask allowing for automatic unattended cask scanning that may take several hours.« less

Scanning moiré fringe (SMF) imaging by high-angle annular dark field scanning transmission electron microscopy was used to measure the strain field in the channel of a transistor with a CoSi2 source and drain. Nanometer-scale SMFs were formed with a scanning grating size of ds at integer multiples of the Si crystal lattice spacing dl (ds ˜ ndl, n = 2, 3, 4, 5). The moiré fringe formula was modified to establish a method for quantifying strain measurement. We showed that strain fields in a transistor measured by SMF images were reproducible with an accuracy of 0.02%.

Isolated hair cell preparations have gained wide acceptance as a model for studying physiological and molecular properties of the sensory cells involved in the hearing process. Ultrastructural details, such as stereocilia links, lateral membrane substructure or synaptic links are of crucial importance for normal sensory transduction. For this reason, we developed a high-resolution scanningelectron microscopy (SEM) procedure to study the surface of isolated hair cells. Cells were mechanically and/or enzymatically separated, isolated and immobilized on cover slips by alcian blue and fixed by 2% glutardialdehyde or 1% OsO4. After dehydration, preparations were critical point-dried and sputter-coated with gold-palladium (2-4 nm). Up to 5 nm resolution was achieved. Optimal fixation kept the cells in their typical cylindrical forms. Preservation of the stereocilia and the apical plates of the outer hair cells depended strongly on the fixation process. Tip- and side-links were observed only sporadically because of the aggressive preparation procedure. The lateral plasma membranes of the cell bodies showed regular granular structures of 5-7 nm diameter at maximal magnification. The granular structure of the cell membrane seemed to correspond to putative transmembrane proteins believed to generate membrane-based motility. The remnants of the nerve endings and/or supporting cells usually covered the cell base. The preservation of the cells was better when enzymatic isolation was omitted. The technique used allowed for high resolution ultrastructural examination of isolated hair cells and, when combined with immunological labeling, may permit the identification of proteins at a molecular level. PMID:9064297

Stone analysis is incompletely done in many clinical centers. Identification of the stone component is essential for deciding future prophylaxis. X-ray diffraction, Fourier transform infrared spectroscopy, and scanningelectron microscopy (SEM) still remains a distant dream for routine hospital work. It is in this context that optical microscopy is suggested as an alternate procedure. The objective of this article was to assess the utility of an optical microscope which gives magnification of up to 40x and gives clear picture of the surface of the stones. In order to authenticate the morphological analysis of urinary stones, SEM and elemental distribution analysis were performed. A total of 250 urinary stones of different compositions were collected from stone clinic, photographed, observed under an optical microscope, and optical photographs were taken at different angles. Twenty-five representative samples among these were gold sputtered to make them conductive and were fed into the SEM machine. Photographs of the samples were taken at different angles at magnifications up to 4,000. Elemental distribution analysis (EDAX) was done to confirm the composition. The observations of the two studies were compared. The different appearances of the stones under optical illuminated microscopy were mostly standardized appearances, namely bosselations of pure whewellite, spiculations of weddellite, bright yellow colored appearance of uric acid, and dirty white amorphous appearance of phosphates. SEM and EDAX gave clearer pictures and gave added confirmation of the stone composition. From the references thus obtained, it was possible to confirm the composition by studying the optical microscopic pictures. Higher magnification capacity of the SEM and the EDAX patterns are useful to give reference support for performing optical microscopy work. After standardization, routine analysis can be performed with optical microscopy. The advantage of the optical microscope is that, it

. Fortunately, many antimicrobial defense systems of higher organisms require sensitive detection to combat microbial pathogens. We employ here the primitive immune system of the evolutionarily ancient horseshoe crab, Limulus polyphemus. This species relies on multi-enzyme signal amplification detection of cell wall molecules and they can be applied to the development of useful detectors of life. An extension of this work includes the visualization of microbial signatures by labeling LAL components with chromogenic or electron dense markers. The protein Limulus Anti-LPS Factor (LALF) has an extremely high affinity for LPS. By coupling LALF binding with colloidal gold labels we demonstrate a correlation of the structures visible by electron microscopy with biochemical evidence of microbial cell wall materials. Pure silica particles were mixed with cultures of E. coli (10(exp 6) cfu/mL). Samples were washed sequentially with buffered saline, LALF, antibody to LALF and finally colloidal gold-labeled Protein A. Negative controls were not exposed to E. coli but received identical treatment otherwise. Samples were coated with carbon and imaged on a JEOL JSM-840 scanningelectron microscope with LaB6 source in the back scatter mode with the JEOL annular back scatter detector. 20 nm-scale black spots in this contrast-reversed image originate from electrons back-scattered by gold atoms. Negative controls did not give any signal. Future work will expand application of this technique to soil simulants and mineralized rock samples.

Systems and methods for conducting electron or scanning probe microscopy are provided herein. In a general embodiment, the systems and methods for conducting electron or scanning probe microscopy with an undersampled data set include: driving an electron beam or probe to scan across a sample and visit a subset of pixel locations of the sample that are randomly or pseudo-randomly designated; determining actual pixel locations on the sample that are visited by the electron beam or probe; and processing data collected by detectors from the visits of the electron beam or probe at the actual pixel locations and recovering a reconstructed image of the sample.

Richard Feynman said "There's plenty of room at the bottom". This inspired the techniques to improve the single molecule measurements. Since the first single molecule study was in 1961, it has been developed in various field and evolved into powerful tools to understand chemical and biological property of molecules. This thesis demonstrates electronic single molecule measurement with Scanning Tunneling Microscopy (STM) and two of applications of STM; Break Junction (BJ) and Recognition Tunneling (RT). First, the two series of carotenoid molecules with four different substituents were investigated to show how substituents relate to the conductance and molecular structure. The measured conductance by STM-BJ shows that Nitrogen induces molecular twist of phenyl distal substituents and conductivity increasing rather than Carbon. Also, the conductivity is adjustable by replacing the sort of residues at phenyl substituents. Next, amino acids and peptides were identified through STM-RT. The distribution of the intuitive features (such as amplitude or width) are mostly overlapped and gives only a little bit higher separation probability than random separation. By generating some features in frequency and cepstrum domain, the classification accuracy was dramatically increased. Because of large data size and many features, supporting vector machine (machine learning algorithm for big data) was used to identify the analyte from a data pool of all analytes RT data. The STM-RT opens a possibility of molecular sequencing in single molecule level. Similarly, carbohydrates were studied by STM-RT. Carbohydrates are difficult to read the sequence, due to their huge number of possible isomeric configurations. This study shows that STM-RT can identify not only isomers of mono-saccharides and disaccharides, but also various mono-saccharides from a data pool of eleven analytes. In addition, the binding affinity between recognition molecule and analyte was investigated by comparing with

The dual beam scanningelectron microscope, equipped with both a focused ion- and scanningelectron- beam (FIB SEM) is a novel tool for the exploration of the subsurface structure of biological tissues. The FIB is capable of removing small cross sections to view the subsurface features and may be s...

In this work the characterization of CMOS diodes with Electron Beam Induced Current (EBIC) measurements in a ScanningElectron Microscope (SEM) are presented. Three-dimensional Technology Computer Aided Design (TCAD) simulations of the EBIC measurement were performed for the first time to help interpret the experimental results. The TCAD simulations provide direct access to the spatial distribution of physical quantities (like mobility, lifetime etc.) which are very difficult to obtain experimentally. For the calibration of the simulation to the experiments, special designs of vertical p-n diodes were fabricated. These structures were investigated with respect to doping concentration, beam energy, and biasing. A strong influence of the surface preparation on the measurements and the extracted diffusion lengths are shown.

Since the pioneering work of Yamamoto, the use of electron spectroscopy such as Cathodoluminescence (CL) and Electron Energy Loss Spectroscopy (EELS) in a Scanning (Transmission) Electron Microscope (STEM) has considerably helped improving our understanding of the optical properties of metallic nanoparticles. The resemblance of spectroscopic signals from electron and pure optical techniques leads to the intuition that both types of techniques are very close, an idea theoretically discussed by F.J. Garcia de Abajo and coworkers. However, it is also quite intuitive that CL and EELS should be different. For example, EELS helps detecting any sort of modes while CL can only detect radiative ones. On the other hand, even between optical spectroscopy techniques, clear differences such as energy shifts or spectral shapes changes are expected in the case of plasmons. The lack of adapted instrumentation capable of performing combined EELS and CL, as well as theoretical developments allowing to account for the generic difference between EELS and CL and their optical counterparts impeached a comprehensive understanding of plasmons physics with the otherwise amazing electron spectroscopies. In this talk, I will present recent experimental results showing combined EELS and CL spectral mapping of plasmonic properties for nanoparticles with several shapes (triangles, cubes, stars...) and composition (gold, silver, aluminum...). Helped with different theoretical tools, I will try to show how these results can be related to their optical counterparts (extinction, scattering), and what type of physical insights can be gained from these combined measurements. Finally, if time allows, pointing the weaknesses of state-of-the-art CL and EELS (in terms of spectral range and/or spectral resolution), I will present EELS results obtained on highly monochromated electron beams that could cope with these limitations

Scanning moiré fringe (SMF) imaging by high-angle annular dark field scanning transmission electron microscopy was used to measure the strain field in the channel of a transistor with a CoSi{sub 2} source and drain. Nanometer-scale SMFs were formed with a scanning grating size of d{sub s} at integer multiples of the Si crystal lattice spacing d{sub l} (d{sub s} ∼ nd{sub l}, n = 2, 3, 4, 5). The moiré fringe formula was modified to establish a method for quantifying strain measurement. We showed that strain fields in a transistor measured by SMF images were reproducible with an accuracy of 0.02%.

Helium gas and air are commonly used in the high pressure scanningelectron microscope (HPSEM). The presence of a gaseous environment in the specimen chamber modifies the electron beam profile. In order to fully understand the beam-gas interaction, we have investigated the beam-diameter effect for two gases (helium and air) by Monte Carlo simulation. In this calculation, we have assumed that the electron beam is Gaussian and we have explored the influence of the nature of the gas at low voltage. When the beam diameter varies between 1 and 100 nm, there is no influence on the beam profile for these two gases. The resolving power of the HPSEM is not affected by the beam-gas interaction. These theoretical results have been compared with experimental images obtained at low voltage under air and helium gases. The variation of image quality at low voltage has confirmed the interest of helium for use in a Field Emission Gun SEM (FEGSEM) in high pressure (or low vacuum) conditions. PMID:15219900

A new image detection system has been developed to display transmission electron microscope (TEM) images on a CRT without a video camera system. Deflection coils placed in both the upper space of an objective lens and in the lower space of the first intermediate lens scan a small electron probe simultaneously. The electrical signal acquired through an improved scintillator and a photomultiplier is synchronized with the scanning signal and displayed in a similar fashion to a conventional scanning TEM (STEM) instrument. A preliminary system using a 100 kV conventional TEM (CTEM) equipped with a hairpin-type electron gun, produced an image with a spatial resolution of 1 nm. PMID:2391565

A variable pressure scanningelectron microscope (VPSEM) can produce a topographic surface relief of a physical object under examination, in addition to its two-dimensional (2D) image. This topographic surface relief is especially helpful when dealing with porous rock because it may elucidate the pore-space structure as well as grain shape and size. Whether the image accurately reproduces the physical object depends on the management of the hardware, acquisition, and postprocessing. Two problems become apparent during testing: (a) a topographic surface relief of a precision ball bearing is distorted and does not correspond to the physical dimensions of the actual sphere and (b) an image of a topographic surface relief of a Berea sandstone is geometrically tilted and topographically distorted even after standard corrections are applied. The procedure presented here is to ensure the veracity of the image, and includes: (a) adjusting the brightness and contrast levels originally provided by the manufacturer and (b) tuning the amplifiers of the backscatter detector plates to be equal to each other, and producing zero voltage when VPSEM is idle. This procedure is tested and verified on the said two physical samples. SCANNING 31: 59-64, 2009. (c) 2009 Wiley Periodicals, Inc. PMID:19204999

In this paper, a new automatic procedure for determining critical recrystallization parameters, which are important when studying recrystallization kinetics, is presented. The method is based on electron backscatter patterns (EBSP) line scans using a scanningelectron microscope, where three parallel lines are scanned. The concepts of equivalence and connectivity are used to group the data points into those originating in recrystallized grains and those originating in the deformed matrix. The computer program implementing the automatic procedure is tested in three different ways: three short scans are performed, where the calculations are also done by hand; the results of two long scans are compared to the direct observation of the microstructure seen in orientation image maps (OIMs) [Mater. Sci. Eng. A. 166 (1993) 59], and the results of scans from a series of samples are compared to statistical results obtained manually. A good correlation was achieved in all three cases.

A confocal scanning transmission electron microscope which includes an electron illumination device providing an incident electron beam propagating in a direction defining a propagation axis, and a precision specimen scanning stage positioned along the propagation axis and movable in at least one direction transverse to the propagation axis. The precision specimen scanning stage is configured for positioning a specimen relative to the incident electron beam. A projector lens receives a transmitted electron beam transmitted through at least part of the specimen and focuses this transmitted beam onto an image plane, where the transmitted beam results from the specimen being illuminated by the incident electron beam. A detection system is placed approximately in the image plane.

The maximum resolution achievable with a scanning probe microscope is limited by the probe size, by the mechanism of interaction with the sample, as is widely known, and by the electronic noise in the instrument. The evaluation of this noise for the three motion axes of a linearized high resolution scanning electrochemical microscope has been carried through and the intrinsic maximum resolution is discussed.

Concerns about the environmental and public health effects of particulate matter (PM) have stimulated interest in analytical techniques capable of measuring the size and chemical composition of individual aerosol particles. Computer-controlled scanningelectron microscopy (CCSE...

Giardia trophozoites were isolated from the small intestine of budgerigars (parakeets) and examined morphologically with light and scanningelectron microscopy. The presence of a claw-hammer shape median body suggested classification of these trophozoites as G. duodenalis. Howeve...

Studies of cellular surface features gain from correlative approaches, where live cell information acquired by fluorescence light microscopy is complemented by ultrastructural information from scanningelectron micrographs. Current approaches to spatially align fluorescence images with scanningelectron micrographs are technically challenging and often cost or time-intensive. Relying exclusively on open-source software and equipment available in a standard lab, we have developed a method for rapid, software-assisted alignment of fluorescence images with the corresponding scanningelectron micrographs via a stochastic gold micro-pattern. Here, we provide detailed instructions for micro-pattern production and image processing, troubleshooting for critical intermediate steps, and examples of membrane ultra-structures aligned with the fluorescence signal of proteins enriched at such sites. Together, the presented method for correlative fluorescence – scanningelectron microscopy is versatile, robust and easily integrated into existing workflows, permitting image alignment with accuracy comparable to existing approaches with negligible investment of time or capital. PMID:26647824

Studies of cellular surface features gain from correlative approaches, where live cell information acquired by fluorescence light microscopy is complemented by ultrastructural information from scanningelectron micrographs. Current approaches to spatially align fluorescence images with scanningelectron micrographs are technically challenging and often cost or time-intensive. Relying exclusively on open-source software and equipment available in a standard lab, we have developed a method for rapid, software-assisted alignment of fluorescence images with the corresponding scanningelectron micrographs via a stochastic gold micro-pattern. Here, we provide detailed instructions for micro-pattern production and image processing, troubleshooting for critical intermediate steps, and examples of membrane ultra-structures aligned with the fluorescence signal of proteins enriched at such sites. Together, the presented method for correlative fluorescence - scanningelectron microscopy is versatile, robust and easily integrated into existing workflows, permitting image alignment with accuracy comparable to existing approaches with negligible investment of time or capital. PMID:26647824

Research into the application of custom doped piezoresistive silicon pressure sensors has led to a multichannel pressure sensor design that will operate accurately and reliably at cryogenic temperatures. The thermal effects upon multichannel pressure sensors are mapped by thermal calibrations and are represented by sets of nth order coefficients specific to each sensor. The thermal offset and sensitivity variations are corrected by computer algorithms which scan the sensors, recall correction coefficients from thermally induced sensor variations, and apply these to correct the sensor's output measurement uncertainty to within 0.5 percent of full scale output for combined offset and sensitivity. A prototype sensor system has been fabricated, and performance test data are presented.

The calcareous concretions of human pineal bodies were investigated with scanningelectron microscopy and electron probe microanalysis. The initial concretions measuring 5-7 microns in diameter may have started at the calcified pinealocytes. They grew appositionally forming concentric laminations, and then the simple calcospherulites over 20 microns occasionally aggregated with each other. Some of them became numerous spherulite-aggregated concretions. Others individually grew with scallop-shaped concentric laminations at intervals of 0.05-1 microns and became lobated calcospherulites up to 0.5 mm. The concretions over 0.5 mm were formed by their attachments. The major elements were Ca and P, while traces of S, Mg, and Na were detected. In the calcification and crystallization values, the center of the concretions over 50 microns was significantly higher than the periphery, while there were no differences among the centers and also among the peripheries. The Ca and P amounts in the center were 30.8% and 14.2% by weight and the Ca/P molar ratio was 1.68; thereby the sand-grain-shaped crystals may be nearly hydroxyapatite, as reported previously. PMID:7699308

A method was developed for measuring nondestructively the depth of planar p-n junctions in simple devices as well as in integrated-circuit structures with the electron-beam induced current (EBIC) by scanning parallel to the junction in a scanningelectron microscope (SEM). The results were found to be in good agreement with those obtained by the commonly used destructive method of lapping at an angle to the junction and staining to reveal the junction.

Plasmonic nanoparticle grating (PNG) structure of different periods has been fabricated by electron beam lithography using silver halide based transmission electron microscope film as a substrate. Conventional scanningelectron microscope is used as a fabrication tool for electron beam lithography. Optical microscope and energy dispersive spectroscopy (EDS) have been used for its morphological and elemental characterization. Optical characterization is performed by UV-Vis absorption spectroscopic technique.

Magnetotactic bacteria are of great interdisciplinary interest, since a vast field of applications from magnetic recording media to medical nanorobots is conceivable. A key feature for a further understanding is the detailed knowledge about the magnetosome chain within the bacteria. We report on two preparation procedures suitable for UHV experiments in reflective geometry. Further, we present the results of scanningelectron microscopy, as well as the first photoemission electron microscopy experiments, both accessing the magnetosomes within intact magnetotactic bacteria and compare these to scanningelectron microscopy data from the literature. From the images, we can clearly identify individual magnetosomes within their chains.

This presentation discusses work done to assess the design of a focusing column in a miniaturized ScanningElectron Microscope (SEM) developed at the NASA Marshall Space Flight Center (MSFC) for use in-situ on the Moon-in particular for mineralogical analysis. The MSFC beam column design uses purely electrostatic fields for focusing, because of the severe constraints on mass and electrical power consumption imposed by the goals of lunar exploration and of spaceflight in general. The resolution of an SEM ultimately depends on the size of the focused spot of the scanning beam probe, for which the stated goal here is a diameter of 10 nanometers. Optical aberrations are the main challenge to this performance goal, because they blur the ideal geometrical optical image of the electron source, effectively widening the ideal spot size of the beam probe. In the present work the optical aberrations of the mini SEM focusing column were assessed using direct tracing of non-paraxial rays, as opposed to mathematical estimates of aberrations based on paraxial ray-traces. The geometrical ray-tracing employed here is completely analogous to ray-tracing as conventionally understood in the realm of photon optics, with the major difference being that in electron optics the lens is simply a smoothly varying electric field in vacuum, formed by precisely machined electrodes. Ray-tracing in this context, therefore, relies upon a model of the electrostatic field inside the focusing column to provide the mathematical description of the "lens" being traced. This work relied fundamentally on the boundary element method (BEM) for this electric field model. In carrying out this research the authors discovered that higher accuracy in the field model was essential if aberrations were to be reliably assessed using direct ray-tracing. This led to some work in testing alternative techniques for modeling the electrostatic field. Ultimately, the necessary accuracy was attained using a BEM

Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. Here, we discuss the application of so-called "big-data" methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature and does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. However, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy. PMID:27211523

Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. Here, we discuss the application of so-called “big-data” methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature and does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. However, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy. PMID:27211523

Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. Here, we discuss the application of so-called “big-data” methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature and does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. However, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy.

Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. In this paper, we discuss the application of so-called “big-data” methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature andmore » does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. Finally, however, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy.« less

The general applicability of power law forms of the background in electron spectra is pointed out and exploited for background removal from under Auger peaks. This form of B(E) is found to be extremely sensitive to instrumental alignment and to fault-free construction - an observation which can be used to set up analyser configurations in an accurate way. Also, differences between N(E) and B(E) can be used to derive a spectrometer transmission function T(E). The questions of information density in an energy-analysing spatially-resolving instrument are addressed after reliable instrumental characterization has been established. Strategies involving ratio histograms, showing the population distribution of the ratio of a pair of Auger peak heights, composition scatter diagrams and windowed imaging are discussed and illustrated.

Pneumoconiosis is often considered a disease of the lung initiated by exposure to dust or other airborne particles, resulting in injury to the lungs. The term "endogenous pneumoconiosis" has been used in the literature to describe the deposition of compounds on the elastic fibers of the lung, usually in the setting of cardiac failure. In the case we present here, the patient aspirated a foreign body resulting in damage to the lung tissue and subsequent deposition of endogenous compounds on the elastic fibers of the pulmonary parenchyma and vasculature. We determined the composition of this mineral and mapped the distribution of elements using a combination of backscattered electron microscopy and energy dispersive spectrometry. PMID:27281119

Electron spin resonance (ESR) spectroscopy's affinity for detecting paramagnetic free radicals, or spins, has been increasingly employed to examine a large variety of biochemical interactions. Such paramagnetic species are broadly found in nature and can be intrinsic (defects in solid-state materials systems, electron/hole pairs, stable radicals in proteins) or, more often, purposefully introduced into the material of interest (doping/attachment of paramagnetic spin labels to biomolecules of interest). Using ESR to trace the reactionary path of paramagnetic spins or spin-active proxy molecules provides detailed information about the reaction's transient species and the label's local environment. For many biochemical systems, like those involving membrane proteins, synthesizing the necessary quantity of spin-labeled biomolecules (typically 50 pmol to 100 pmol) is quite challenging and often limits the possible biochemical reactions available for investigation. Quite simply, ESR is too insensitive. Here, we demonstrate an innovative approach that greatly enhances ESR's sensitivity (>20000× improvement) by developing a near-field, nonresonant, X-band ESR spectrometric method. Sensitivity improvement is confirmed via measurement of 140 amol of the most common nitroxide spin label in a ≈593 fL liquid cell at ambient temperature and pressure. This experimental approach eliminates many of the typical ESR sample restrictions imposed by conventional resonator-based ESR detection and renders the technique feasible for spatially resolved measurements on a wider variety of biochemical samples. Thus, our approach broadens the pool of possible biochemical and structural biology studies, as well as greatly enhances the analytical power of existing ESR applications. PMID:25867553

Electron detection characteristics are summarized for the slow scan CCD (SSC) camera, imaging plates, and film. The advantage of each detector is demonstrated with the selected examples of electron diffraction and imaging. The Richardson-Lucy algorithm for image restoration is described and tested for images recorded with the SSC camera. The effectiveness of image restoration is demonstrated for the recorded high-resolution lattice image, energy-loss spectrum, and convergent beam electron diffraction (CBED) pattern. PMID:10816266

The structure of lithium niobate single crystals is studied by a complex technique that combines scanningelectron microscopy and atomic force microscopy. By implementing the piezoresponse force method on an atomic force microscope, the domain structure of lithium niobate crystals, which was not revealed without electron beam irradiation, is visualized

Software and hardware updates to further extend the capability of the electron microscope were carried out. A range of materials such as intermetallics, metal-matrix composites, ceramic-matrix composites, ceramics and intermetallic compounds, based on refractory elements were examined under this research. Crystal structure, size, shape and volume fraction distribution of various phases which constitute the microstructures were examined. Deformed materials were studied to understand the effect of interfacial microstructure on the deformation and fracture behavior of these materials. Specimens tested for a range of mechanical property requirements, such as stress rupture, creep, low cycle fatigue, high cycle fatigue, thermomechanical fatigue, etc. were examined. Microstructural and microchemical stability of these materials exposed to simulated operating environments were investigated. The EOIM Shuttle post-flight samples were also examined to understand the influence of low gravity processing on microstructure. In addition, fractographic analyses of Nb-Zr-W, titanium aluminide, molybdenum silicide and silicon carbide samples were carried out. Extensive characterization of sapphire fibers in the fiber-reinforced composites made by powder cloth processing was made. Finally, pressure infiltration casting of metal-matrix composites was carried out.

Thermal scanningelectron microscopy is a recently developed temperature mapping technique based on thermal diffuse scattering in electron backscatter diffraction in a scanningelectron microscope. It provides nano-scale and non-contact temperature mapping capabilities. Due to the specific temperature sensitive mechanism inherent to this technique, the temperature resolution is highly material dependent. A thorough investigation of what material properties affect the temperature resolution is important for realizing the inherent temperature resolution limit for each material. In this paper, three material dependent parameters-the Debye-Waller B-factor temperature sensitivity, backscatter yield, and lattice constant-are shown to control the temperature resolution.

Experiments using the CL imaging mode to recognise osteoid in the polished, cut surfaces of bone biopsies embedded in PMMA led to the development of a number of new methods for contrast formation in CL images in the SEM. These involve: (1) enhancing or (2) reducing the CL signal by staining the specimen, (3) utilising the cathodoluminescence of glass microscope slides to produce images of histological sections mounted on glass so that features in the section which scatter the electron beam appear dark against a light background, and (4) enhancing the CL signal from PMMA so that features which are less penetrated by the scintillator show up dark against a bright background. Efforts to increase the efficiency of light collection resulted in the development of a new means for manufacturing reflector-cum-light guide CL detectors by wrapping aluminum foil around a wooden former. These detectors enshroud the specimen so that CL light can only escape to the photomultiplier window (or back up the final lens). A variety of such designs have proved more efficient than the conventional plastic light guides used as CL detectors. By enlarging the beam entry aperture, other SE and BSE detectors can be used simultaneously. Examples of the value of the CL mode in mineralised tissue research include the use of enhanced CL plastic embedding media to detect marrow space and of enhanced osteoid CL to detect unmineralised bone matrix; the use of tetracycline as a growth marker in pathological studies of bone and experimental studies with bone, dentine and enamel; the use of bisbenzamid to locate and count nuclei in osteoclasts, the hard tissue resorbtive cells; and the use of superficial stain absorption of auto-CL to locate stained material on tooth surfaces, with the view to monitor the efficiency of periodontal therapy. PMID:6669948

Correlative light electron microscopy (CLEM) combines the advantages of light and electron microscopy, thus making it possible to follow dynamic events in living cells at nanometre resolution. Various CLEM approaches and devices have been developed, each of which has its own advantages and technical challenges. We here describe our customized patterned glass substrates, which improve the feasibility of correlative fluorescence/confocal and scanningelectron microscopy. PMID:25391455

Correlative light electron microscopy (CLEM) combines the advantages of light and electron microscopy, thus making it possible to follow dynamic events in living cells at nanometre resolution. Various CLEM approaches and devices have been developed, each of which has its own advantages and technical challenges. We here describe our customized patterned glass substrates, which improve the feasibility of correlative fluorescence/confocal and scanningelectron microscopy.

Nanotechnology places increasing demands on techniques for sample characterisation on the sub-100 nm length scale, and the low-loss electron (LLE) signal may provide one possible way of addressing this need. Simulations of the LLE signal from a line-scan across a semiconductor superlattice structure have been performed using two different Monte Carlo models in order to assess their effectiveness in predicting spatial resolution for compositional imaging. Additionally, experimental measurements of LLE data using a detector added to a scanningelectron microscope were made to investigate compositional contrast.

Detailed optical scanning of tray clamps is being conducted in the Facility for the Optical Inspection of Large Surfaces at JSC to locate and document impacts as small as 40 microns in diameter. Residues from selected impacts are then being characterized by ScanningElectron Microscopy/Energy Dispersive X-ray Analysis at CNES. Results from this analysis will be the initial step to classifying projectile residues into specific sources.

Projections for 2D spectral-spatial images were obtained by continuous wave and rapid-scanelectron paramagnetic resonance using a bimodal cross-loop resonator at 251 MHz. The phantom consisted of three 4 mm tubes containing different 15N,2H-substituted nitroxides. Rapid-scan and continuous wave images were obtained with 5 min total acquisition times. For comparison, images also were obtained with 29 s acquisition time for rapid scan and 15 min for continuous wave. Relative to continuous wave projections obtained for the same data acquisition time, rapid-scan projections had significantly less low-frequency noise and substantially higher signal-to-noise at higher gradients. Because of the improved image quality for the same data acquisition time, linewidths could be determined more accurately from the rapid-scan images than from the continuous wave images. PMID:24650729

The electron transport and structural properties of nanostructured materials have been examined with a newly developed low temperature quadraprobe scanning tunneling microscope (STM) system. The quadraprobe STM system, as a "nano" version of a four-probe station provides an integrated research platform with a low temperature four-probe STM, a molecular-beam epitaxy growth chamber, a high resolution scanningelectron microscope, and a scanning Auger microscope. The four STM probes can be driven independently with sub-nanometer precision, enabling conventional STM imaging and four-point electrical transport study of surface electronic systems and nanostructured materials at temperatures down to 10 K. Self-assembled nanostructures grown on Si by doping with metal atoms (Au, Gd, Ag) have been fabricated and characterized in situ.

Although scanning confocal electron microscopy (SCEM) shows a promise for optical depth sectioning with high resolution, practical and theoretical problems have prevented its application to three-dimensional (3D) imaging. We employed a stage-scanning system in which only the specimen is moved three dimensionally under a fixed lens configuration, and an annular dark-field (ADF) aperture which blocks direct beams and selects only the scattered electrons. This ADF-SCEM improved depth resolution sufficiently to perform optical depth sectioning. Finally, we succeeded in demonstrating the 3D reconstruction of carbon nanocoils using ADF-SCEM.

Bat wings are highly adaptive airfoils that enable demanding flight maneuvers, which are performed with astonishing robustness under turbulent conditions, and stability at slow flight velocities. The bat wing is sparsely covered with microscopically small, sensory hairs that are associated with tactile receptors. In a previous study we demonstrated that bat wing hairs are involved in sensing airflow for improved flight maneuverability. Here, we report physical measurements of these hairs and their distribution on the wing surface of the big brown bat, Eptesicus fuscus, based on scanningelectron microscopy analyses. The wing hairs are strongly tapered, and are found on both the dorsal and ventral wing surfaces. Laser scanning vibrometry tests of 43 hairs from twelve locations across the wing of the big brown bat revealed that their natural frequencies inversely correlate with length and range from 3.7 to 84.5 kHz. Young's modulus of the average wing hair was calculated at 4.4 GPa, which is comparable with rat whiskers or arthropod airflow-sensing hairs. PMID:27545727

Confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and soft X-ray scanning transmission X-ray microscopy (STXM) were used to map the distribution of macromolecular subcomponents (e.g., polysaccharides, proteins, lipids, and nucleic acids) of biofilm cells and matrix. The biofilms were developed from river water supplemented with methanol, and although they comprised a complex microbial community, the biofilms were dominated by heterotrophic bacteria. TEM provided the highest-resolution structural imaging, CLSM provided detailed compositional information when used in conjunction with molecular probes, and STXM provided compositional mapping of macromolecule distributions without the addition of probes. By examining exactly the same region of a sample with combinations of these techniques (STXM with CLSM and STXM with TEM), we demonstrate that this combination of multimicroscopy analysis can be used to create a detailed correlative map of biofilm structure and composition. We are using these correlative techniques to improve our understanding of the biochemical basis for biofilm organization and to assist studies intended to investigate and optimize biofilms for environmental remediation applications. PMID:12957944

Ferroelectric domain nucleation and growth in multiferroic BiFeO{sub 3} films is observed directly by applying a local electric field with a conductive tip inside a scanning transmission electron microscope. The nucleation and growth of a ferroelastic domain and its interaction with pre-existing 71{sup o} domain walls are observed and compared with the results of phase-field modeling. In particular, a preferential nucleation site and direction-dependent pinning of domain walls are observed due to slow kinetics of metastable switching in the sample without a bottom electrode. These in situ spatially resolved observations of a first-order bias-induced phase transition reveal the mesoscopic mechanisms underpinning functionality of a wide range of multiferroic materials.

There are linear accelerators (Sagittaire and Saturne accelerators produced by Compagnie Generale de Radiologie (CGR/MeV) Corporation) which produce broad, flat electron fields by magnetically scanning the relatively narrow electron beam as it emerges from the accelerator vacuum system. A semi-empirical model, which mimics the scanning action of this type of accelerator, was developed for the generation of dose distributions in homogeneous media. The model employs the dose distributions of the scanningelectron beams. These were measured with photographic film in a polystyrene phantom by turning off the magnetic scanning system. The mean deviation calculated from measured dose distributions is about 0.2%; a few points have deviations as large as 2 to 4% inside of the 50% isodose curve, but less than 8% outside of the 50% isodose curve. The model has been used to generate the electron beam library required by a modified version of a commercially-available computerized treatment-planning system. (The RAD-8 treatment planning system was purchased from the Digital Equipment Corporation. It is currently available from Electronic Music Industries (EMI), Ltd.)

We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than the size of the incident electron beam. PMID:27587179

Three-dimensional (3D) reconstructions from electron tomography provide important morphological, compositional, optical and electro-magnetic information across a wide range of materials and devices. Precession electron diffraction, in combination with scanning transmission electron microscopy, can be used to elucidate the local orientation of crystalline materials. Here we show, using the example of a Ni-base superalloy, that combining these techniques and extending them to three dimensions, to produce scanning precession electron tomography, enables the 3D orientation of nanoscale sub-volumes to be determined and provides a one-to-one correspondence between 3D real space and 3D reciprocal space for almost any polycrystalline or multi-phase material. PMID:26028514

Three-dimensional (3D) reconstructions from electron tomography provide important morphological, compositional, optical and electro-magnetic information across a wide range of materials and devices. Precession electron diffraction, in combination with scanning transmission electron microscopy, can be used to elucidate the local orientation of crystalline materials. Here we show, using the example of a Ni-base superalloy, that combining these techniques and extending them to three dimensions, to produce scanning precession electron tomography, enables the 3D orientation of nanoscale sub-volumes to be determined and provides a one-to-one correspondence between 3D real space and 3D reciprocal space for almost any polycrystalline or multi-phase material. PMID:26028514

We report a novel scanning probe electron energy spectrometer (SPEES) which combines a double toroidal analyzer with a scanning tunneling microscope to achieve both topography imaging and electron energy spectroscopy mapping of surface in situ. The spatial resolution of spectroscopy mapping is determined to be better than 0.7 ± 0.2 μm at a tip sample distance of 7 μm. Meanwhile, the size of the field emission electron beam spot on the surface is also measured, and is about 3.6 ± 0.8 μm in diameter. This unambiguously demonstrates that the spatial resolution of SPEES technique can be much better than the size of the incident electron beam.

Electron-excited x-ray microanalysis performed in the variable pressure and environmental scanningelectron microscopes is subject to additional artifacts beyond those encountered in the conventional scanningelectron microscope. Gas scattering leads to direct contributions to the spectrum from the environmental gas, as well as remote generation of x rays by electrons scattered out of the focussed beam. The analyst can exert some degree of control over these artifacts, but depending on the exact situation, spurious elements can appear at the trace (< 0.01 mass fraction), minor (0.01 mass fraction to 0.1 mass fraction), or even major (> 0.1 mass fraction) levels. Dispersed particle samples give the least compromised results, while fine scale microstructures are the most severely compromised. Procedures to optimize the situation based upon specimen preparation as well as spectral processing are described. PMID:27446754

ScanningElectron Microscopy combined with electron-induced X-ray Fluorescence Spectroscopy (SEM-EDX) is one of the most powerful techniques for characterizing sub-µm surface morphology and composition. In terrestrial laboratories, SEM-EDX is used to elucidate natural processes such as low-temperature diagenesis, thermal or pressure induced metamorphism, volcanism/magmatism, atmosphere/crust interaction and biological activity. Such information would be highly useful for investigating the natural history of the terrestrial planets, satellites and primitive bodies, providing morphological and elemental information that is 2 orders of magnitude higher in resolution than optical techniques. Below we describe the development of a Micro-column ScanningElectron Microscope and X-ray Spectrometer (MSEMS) for flight. The enabling technology of the MSEMS is a carbon nanotube field emission (CNTFE) electron source that is integrated with micro-electro-mechanical-systems (MEMS) - based electron gun and electron optical structures. A hallmark of CNTFE electron sources is their low chromatic aberration, which reduces the need for high accelerating voltages to obtain small spot size. The CNTFE also offers exceptional brightness and nanometer source size, eliminating the need for condenser lenses, making simple electrostatic focusing optics possible. Moreover, the CNT field emission gun (CFEG) at low operating voltage dissipates 103 less power than thermally-assisted Schottky emitters. A key feature of the MSEMS design is the lack of scanning coils. Rather, a piezoelectric sample stage capable of sub-nanometer resolution scans the sample past the fixed crossover of the MSEMS electron beam. We will describe a MEMS-based templating technique for fabricating mechanically and electrically stable miniature CFEGs. Using existing silicon (Si) technology, we fabricated highly controlled and precise MEMS structures for both the CNT cathode and focusing optics for the micro-column. The

Despite being an excellent tool for investigating ultrastructure, scanningelectron microscopy (SEM) is less frequently used than transmission electron microscopy for microbes such as viruses or bacteria. Here we describe rapid methods that allow SEM imaging of fully hydrated, unfixed microbes without using conventional sample preparation methods. We demonstrate improved ultrastructural preservation, with greatly reduced dehydration and shrinkage, for specimens including bacteria and viruses such as Ebola virus using infiltration with ionic liquid on conducting filter substrates for SEM. PMID:27212232

Despite being an excellent tool for investigating ultrastructure, scanningelectron microscopy (SEM) is less frequently used than transmission electron microscopy for microbes such as viruses or bacteria. Here we describe rapid methods that allow SEM imaging of fully hydrated, unfixed microbes without using conventional sample preparation methods. We demonstrate improved ultrastructural preservation, with greatly reduced dehydration and shrinkage, for specimens including bacteria and viruses such as Ebola virus using infiltration with ionic liquid on conducting filter substrates for SEM. PMID:27212232

By recording low-noise energy-dispersive x-ray spectroscopy maps from crystalline specimens using aberration-corrected scanning transmission electron microscopy, it is possible to probe core-level electron orbitals in real space. Both the 1 s and 2 p orbitals of Sr and Ti atoms in SrTi O3 are probed, and their projected excitation potentials are determined. This paper also demonstrates experimental measurement of the electronic excitation impact parameter and the delocalization of an excitation due to Coulombic beam-orbital interaction.

We describe a hybrid pixel array detector (electron microscope pixel array detector, or EMPAD) adapted for use in electron microscope applications, especially as a universal detector for scanning transmission electron microscopy. The 128×128 pixel detector consists of a 500 µm thick silicon diode array bump-bonded pixel-by-pixel to an application-specific integrated circuit. The in-pixel circuitry provides a 1,000,000:1 dynamic range within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity. A 1.1 kHz framing rate enables rapid data collection and minimizes sample drift distortions while scanning. By capturing the entire unsaturated diffraction pattern in scanning mode, one can simultaneously capture bright field, dark field, and phase contrast information, as well as being able to analyze the full scattering distribution, allowing true center of mass imaging. The scattering is recorded on an absolute scale, so that information such as local sample thickness can be directly determined. This paper describes the detector architecture, data acquisition system, and preliminary results from experiments with 80-200 keV electron beams. PMID:26750260

Noise is a primary issue in obtaining an image in a scanning microscope. This noise needs to be minimized in order to have a clear image of the sample in case of a nanosize level measurement. In this work, we propose a method to improve the image quality by applying dither signal injection to the scanning signal. This method involves minimizing the noise that occurs in scan control circuits, which results in a blurry or distorted image. The collected secondary electrons are first multiplied through a photomultiplier tube and are then converted into digital form using an analog/digital (A/D) converter. We propose a solution for the noise from the scan control circuit that appears on the image by adopting the spread spectrum method. PMID:21990426

The concept of compressed sensing was recently proposed to significantly reduce the electron dose in scanning transmission electron microscopy (STEM) while still maintaining the main features in the image. Here, an experimental setup based on an electromagnetic beam blanker placed in the condenser plane of a STEM is proposed. The beam blanker deflects the beam with a random pattern, while the scanning coils are moving the beam in the usual scan pattern. Experimental images at both the medium scale and high resolution are acquired and reconstructed based on a discrete cosine algorithm. The obtained results confirm that compressed sensing is highly attractive to limit beam damage in experimental STEM even though some remaining artifacts need to be resolved.

Scanningelectron micrographs were taken of sets of human molars-those of paleo-Indians used in mastication of, ostensibly, a highly abrasive diet, and those of contemporary Americans. Different ultrastructural patterns of enamel wear were observed between the groups. PMID:1090642

The grasping spines and teeth of 6 species of Chaetognatha have been studied with the scanningelectron microscope, describing in the grasping spines: curvature, surface, ridge and insertion and in the teeth, its characters and their arrangement on the head. PMID:507374

A scanningelectron microscope photograph of a four-micron size iron crystal growing on a pyroxene crystal (calcium-magnesium-iron silicate) from the Apollo 15 Hadley-Apennino lunar landing site. The well developed crystal faces indicate that the crystal was formed from a hot vapor as the rock was cooling.

This review covers recent experimental progress in probing the electronic properties of graphene and how they are influenced by various substrates, by the presence of a magnetic field and by the proximity to a superconductor. The focus is on results obtained using scanning tunneling microscopy, spectroscopy, transport and magnetotransport techniques.

Mercuric iodide X-ray detectors have been undergoing tests in a prototype scanningelectron microscope system being developed for unmanned space flight. The detector program addresses the issues of geometric configuration in the SEM, compact packaging that includes separate thermoelectric coolers for the detector and FET, X-ray transparent hermetic encapsulation and electrical contacts, and a clean vacuum environment.

Worn nozzles on spray equipment severely affect efficiency of crop management system while causing unnecessary pesticide contamination of non-target areas. Scanningelectron microscopy and x-ray microanalysis that have been used to directly measure pesticide deposition, was used to observe both wor...

This paper describes a new method of magnifying small images in photographic film by means of a scanningelectron microscope (SEM) operated in the backscattered electron detection mode. The study included tests of several types of radiographic film, transmission electron microscopy film, and black and white 35 mm film. The electron optical enlargement method is particularly useful in situations where the film sample is opaque to light and for generating enlarged images at magnifications beyond the reach of light optical enlargement methods, i.e. up to approximately 2000X with ease and rapidity in a single step. The electron optical enlargements compare favorably in contrast and detail with the enlargements made with a light microscope and with a darkroom enlarger.

A high-brightness electron beam of more than 10{sup 11} A sr{sup -1} m{sup -2} was achieved from a graphite nanoneedle cathode, which was fabricated by simple hydrogen plasma etching of a graphite rod. A field emission was obtained at a high residual pressure of 10{sup -6} Torr. The performance of this cold cathode was demonstrated by the fabrication of a scanningelectron microscope, which was operated at a high residual pressure of 10{sup -5}-10{sup -6} Torr. The brightness of this cathode offers a convenient field electron emission source that does not require a massive ultrahigh vacuum system.

Correlating in vivo imaging of neurons and their synaptic connections with electron microscopy combines dynamic and ultrastructural information. Here we describe a semi-automated technique whereby volumes of brain tissue containing axons and dendrites, previously studied in vivo, are subsequently imaged in three dimensions with focused ion beam scanningelectron microcopy. These neurites are then identified and reconstructed automatically from the image series using the latest segmentation algorithms. The fast and reliable imaging and reconstruction technique avoids any specific labeling to identify the features of interest in the electron microscope, and optimises their preservation and staining for 3D analysis. PMID:23468982

Silicon nitride membranes can be used for windows of environmental chambers for in situ electron microscopy. We report that aberration corrected scanning transmission electron microscopy (STEM) achieved atomic resolution on gold nanoparticles placed on both sides of a 50-nm-thick silicon nitride membrane at 200 keV electron beam energy. Spatial frequencies of 1/1.2 A were visible for a beam semi-angle of 26.5 mrad. Imaging though a 100-nm-thick membrane was also tested. The achieved imaging contrast was evaluated using Monte Carlo simulations of the STEM imaging of a sample of with a representative geometry and composition.

The successful integration of electron detection into an existing scanning transmission x-ray microspectroscope (STXM) at the Swiss Light Source is demonstrated. In conventional x-ray detection using a photomultiplier, STXM offers mainly bulk sensitivity combined with high lateral resolution. However, by implementation of a channeltron electron multiplier, the surface sensitivity can be established by the detection of secondary electrons emitted from the sample upon resonant excitation. We describe the experimental setup and discuss several relevant aspects, in particular the schemes to correct for self-absorption in the specimen due to back illumination in case of thicker films. PMID:20370182

The demand to produce electrical power with higher efficiency and with lower environmental pollution is leading to the use of new advanced materials in the production of power plant equipment. To understand the processes taking place in parts produced from these materials during their operation under severe conditions (such as high temperature, high stress, and environmental corrosion) requires detailed evaluation of their substructure. It is usually necessary to use transmission electron microscopy (TEM). However, this method is very exacting and time-consuming. So there is an effort to use new scanningelectron microscopy techniques instead of TEM. One of them is scanning low energy electron microscopy (SLEEM). This paper deals with an assessment of the possibility to use SLEEM for describing the substructure of creep resistant steel CB2 after long-term creep testing. In the SLEEM images more information is contained about the microstructure of the material in comparison with standard scanningelectron microscopy. Study of materials using slow and very slow electrons opens the way to better understanding their microstructures.

With the development of science and technology, field emission scanningelectron microscope (FESEM) plays an important role in nano-material measurements because of its advantages of high magnification, high resolution and easy operation. A high-quality secondary electron image is a significant prerequisite for accurate and precise length measurements. In order to obtain high-quality secondary electron images, the conventional treatment method for non-conductive materials is coating conductive films with gold, carbon or platinum to reduce charging effects, but this method will cover real micro structures of materials, change the sample composition properties and meanwhile introduce a relatively big error to nano-scale microstructure measurements. This paper discusses how to reduce or eliminate the impact of charging effects on image quality to the greatest extent by changing working conditions, such as voltage, stage bias, scanning mode and so on without treatment of coating, to obtain real and high-quality microstructure information of materials.

Scanningelectron microscopy combined with microchemical analysis has evolved into one of the most widely used instruments in forensic science today. In particular, the environmental scanningelectron microscope (SEM) in conjunction with energy dispersive spectroscopy (EDS), has created unique opportunities in forensic science in regard to the examination of trace evidence; i.e. the examination of evidence without altering the evidence with conductive coatings, thereby enabling criminalists to solve cases that were previously considered unsolvable. Two cold cases were solved at URI using a JEOL 5900 LV SEM in conjunction with EDS. A cold case murder and a cold missing person case will be presented from the viewpoint of the microscopist and will include sample preparation, as well as image and chemical analysis of the trace evidence using electron microscopy and optical microscopy.

We show here that upconversion phosphors can be imaged both by infrared excitation and in a scanningelectron microscope. We have synthesized and characterized for this work up-converting phosphor nanoparticles nonaggregated nanocrystals of size range 50-200 nm. We have investigated the optical properties of 50-200 nm nanoparticles and found a square dependence of the emitted visible fluorescence on the infrared excitation and verified that under electron excitation similar narrow band emission spectra can be obtained as is seen with IR upconversion. The viability of the nanoparticles for biological imaging was confirmed by imaging the digestive system of the nematode worm Caenorhabditis elegans, and we have confirmed using energy-dispersive X-ray analysis that the up-conversion nanoparticles can be identified in a scanningelectron microscope at high spatial resolution. PMID:16464029

Correlated electron states in high mobility two-dimensional electron systems (2DESs), including charge density waves and microemulsion phases intermediate between a Fermi liquid and Wigner crystal, are predicted to exhibit complex local charge order. Existing experimental studies, however, have mainly probed these systems at micron to millimeter scales rather than directly mapping spatial organization. Scanning probes should be well-suited to study the spatial structure of these states, but high mobility 2DESs are found at buried semiconductor interfaces, beyond the reach of conventional scanning tunneling microscopy. Scanning techniques based on electrostatic coupling to the 2DES deliver important insights, but generally with resolution limited by the depth of the 2DES. In this letter, we present our progress in developing a technique called “virtual scanning tunneling microscopy” that allows local tunneling into a high mobility 2DES. Using a specially designed bilayer GaAs/AlGaAs heterostructure where the tunnel coupling between two separate 2DESs is tunable via electrostatic gating, combined with a scanning gate, we show that the local tunneling can be controlled with sub-250 nm resolution.

Correlated electron states in high mobility two-dimensional electron systems (2DESs), including charge density waves and microemulsion phases intermediate between a Fermi liquid and Wigner crystal, are predicted to exhibit complex local charge order. Existing experimental studies, however, have mainly probed these systems at micron to millimeter scales rather than directly mapping spatial organization. Scanning probes should be well-suited to study the spatial structure of these states, but high mobility 2DESs are found at buried semiconductor interfaces, beyond the reach of conventional scanning tunneling microscopy. Scanning techniques based on electrostatic coupling to the 2DES deliver important insights, but generally with resolution limited by the depth of the 2DES. In this letter, we present our progress in developing a technique called "virtual scanning tunneling microscopy" that allows local tunneling into a high mobility 2DES. Using a specially designed bilayer GaAs/AlGaAs heterostructure where the tunnel coupling between two separate 2DESs is tunable via electrostatic gating, combined with a scanning gate, we show that the local tunneling can be controlled with sub-250 nm resolution.

The stability of the polar Zn-terminated ZnO surface is probed by low-temperature scanning tunneling microscopy and scanning tunneling spectroscopy (STS). Surface states in the bandgap of ZnO are evidenced by STS and their presence is correlated with the local surface corrugation. Very defective surface regions are characterized by a bulk electronic structure showing a wide bandgap while nanometer-scale defect free regions exhibit a narrower bandgap and surface states. We also image atomically resolved (√3 ×√3 )R30° reconstructions on the defect-free areas.

An organic compound, originally marketed as an antistatic, can form an extremely thin electro-conductive coating upon drying. A scanningelectron microscope (SEM) application for this compound was first explored in the late 1960s. A coating of this compound eliminates the need for carbon or gold coating in some applications. It is well suited for the viewing of fabric samples and associated gunshot residue (GSR) in the SEM and makes it possible to quickly analyze fabric bullet wipe and bore wipe GSR. Fabric samples can also be examined for GSR from intermediate-range shots to estimate muzzle-target distances. Scanning

A "scanning" drift tube apparatus, capable of mapping of the spatiotemporal evolution of electron swarms, developing between two plane electrodes under the effect of a homogeneous electric field, is presented. The electron swarms are initiated by photoelectron pulses and the temporal distributions of the electron flux are recorded while the electrode gap length (at a fixed electric field strength) is varied. Operation of the system is tested and verified with argon gas; the measured data are used for the evaluation of the electron bulk drift velocity. The experimental results for the space-time maps of the electron swarms — presented here for the first time — also allow clear observation of deviations from hydrodynamic transport. The swarm maps are also reproduced by particle simulations.

The fabrication of solid-state nanopores using the electron beam of a transmission electron microscope (TEM) has been reported in the past. Here, we report a similar method to fabricate solid-state nanopores using the electron source of a conventional field-emission scanningelectron microscope (FESEM) instead. Micromachining was used to create initial pore diameters between 50 nm and 200 nm, and controlled pore shrinking to sub 10 nm diameters was performed subsequently during in situ processing in the FESEM. Noticeably, different shrinking behavior was observed when using irradiation from the electron source of the FESEM than the TEM. Unlike previous reports of TEM mediated pore shrinkage, the mechanism of pore shrinkage when using the FESEM could be a result of surface defects generated by radiolysis and subsequent motion of silicon atoms to the pore periphery.

A "scanning" drift tube apparatus, capable of mapping of the spatiotemporal evolution of electron swarms, developing between two plane electrodes under the effect of a homogeneous electric field, is presented. The electron swarms are initiated by photoelectron pulses and the temporal distributions of the electron flux are recorded while the electrode gap length (at a fixed electric field strength) is varied. Operation of the system is tested and verified with argon gas; the measured data are used for the evaluation of the electron bulk drift velocity. The experimental results for the space-time maps of the electron swarms - presented here for the first time - also allow clear observation of deviations from hydrodynamic transport. The swarm maps are also reproduced by particle simulations. PMID:27370421

For identification of the atomic species on a sample surface with high spatial resolution, we developed a field emission scanning tunneling microscopy (FE-STM) combined with an energy analyzer to perform surface electron spectroscopy: the primary electrons are field-emitted from the STM tip to excite sample surfaces. The energy spectra of backscattered electrons obtained using this combined instrument exhibited the elemental features, though the energy peaks and their signal height in the spectra were affected by the electric field between the tip and the sample. In the present study, we have examined and improved the electric shield of an STM tip holder. The metal parts of the holder at a high voltage, which face the gap left for electrons to pass through, were shielded to reduce the electric field. We have successfully demonstrated the effect of the field reduction for surface electron spectroscopy with the FE-STM.

Comparative studies on the ultimate spatial resolution of the ScanningElectron Microscope, using different components of the electron signal have been performed on specimens providing compositional contrast. By operating the microscope in conventional way as well as with a specifically designed set-up we have ascertained that the delocalized components of the signal provide a spatial resolution of the order of the beam size, even if the practical use can be limited by the noise. To amplify the contribution of the delocalized components of the signal, as backscattered electrons by a bulk specimen or forward scattered electrons by a thin specimen, we used a device consisting of a plate of a material with high secondary yield placed above or below the sample. An important practical implication arises from this study. A detecting system consisting of a standard Everhart-Thornley detector coupled with a converter of backscattered or transmitted electrons represents a high performance detecting device for low voltage observations. PMID:8961547

In this work we present a study of the thermal processes taking place during surface modification of steels performed by a scanningelectron beam. The model is based on solving the heat transfer equation by means of Green functions. The thermal field was calculated, together with the size of the zone of structural changes in tool steel samples. The comparison of the zones of thermal treatment as experimentally obtained and theoretically calculated and the corresponding structural changes show a very good agreement.

We demonstrate that a transmission electron microscope fitted with two spherical-aberration correctors can be operated as an energy-filtered scanning confocal electron microscope. A method for establishing this mode is described and initial results showing 3D chemical mapping with nanoscale sensitivity to height and thickness changes in a carbon film are presented. Importantly, uncorrected chromatic aberration does not limit the depth resolution of this technique and moreover performs an energy-filtering role, which is explained in terms of a combined depth and energy-loss response function.

We assess scanningelectron microscopy (SEM) and Auger electron spectroscopy (AES) for thickness measurements on few-layer hexagonal boron nitride (h-BN), the layered dielectric of choice for integration with graphene and other two-dimensional materials. Observations on h-BN islands with large, atomically flat terraces show that the secondary electron intensity in SEM reflects monolayer height changes in films up to least 10 atomic layers thickness. From a quantitative analysis of AES data, the energy-dependent electron escape depth in h-BN films is deduced. The results show that AES is suitable for absolute thickness measurements of few-layer h-BN of 1 to 6 layers.

Whole cells can be studied in their native liquid environment using electron microscopy, and unique information about the locations and stoichiometry of individual membrane proteins can be obtained from many cells thus taking cell heterogeneity into account. Of key importance for the further development of this microscopy technology is knowledge about the effect of electron beam radiation on the samples under investigation. We used environmental scanningelectron microscopy (ESEM) with scanning transmission electron microscopy (STEM) detection to examine the effect of radiation for whole fixed COS7 fibroblasts in liquid. The main observation was the localization of nanoparticle labels attached to epidermal growth factor receptors (EGFRs). It was found that the relative distances between the labels remained mostly unchanged (<1.5%) for electron doses ranging from the undamaged native state at 10 e-/Å2 toward 103 e-/Å2. This dose range was sufficient to determine the EGFR locations with nanometer resolution and to distinguish between monomers and dimers. Various different forms of radiation damage became visible at higher doses, including severe dislocation, and the dissolution of labels. PMID:27137077

Electrostatic driven 2D MEMS scanners resonantly oscillate in both axes leading to Lissajous trajectories of a digitally modulated laser beam reflected from the micro mirror. A solid angle of about 0.02 is scanned by a 658nm laser beam with a maximum repetition rate of 350MHz digital pulses. Reflected light is detected by an APD with a bandwidth of 80MHz. The phase difference between the scanned laser light and the light reflected from an obstacle is analyzed by sub-Nyquist sampling. The FPGA-based electronics and software for the evaluation of distance and velocity of objects within the scanning range are presented. Furthermore, the measures to optimize the Lidar accuracy of about 1mm and the dynamic range of up to 2m are examined. First measurements demonstrating the capability of the system and the evaluation algorithms are discussed.

A two-stage model is presented to describe alloy element evaporation rates from molten metal due to transient local heating by an electron beam. The first stage is a simulation of transient phenomena near the melt surface due to periodic heating by a scanning beam, the output of which is the relationship between operating parameters, surface temperature, and evaporation rate. At high scan rates, this can be done using a simple one-dimensional heat transfer model of the surface layer; at lower scan rates, a more complex three-dimensional model with fluid flow and periodic boundary conditions is necessary. The second stage couples this evaporation-surface temperature relationship with a larger steady state heat transfer and fluid flow model of an entire melting hearth or mold, in order to calculate local and total evaporation rates. Predictions are compared with experimental results from Sandia`s 310-kW electron beam melting furnace, in which evaporation rates and vapor compositions were studied in pure titanium and Ti-6%Al-4%V alloy. Evaporation rates were estimated from rate of condensation on a substrate held over the hearth, and were characterized as a function of beam power (150 and 225 kW), scan frequency (30, 115 and 450 Hz) and background pressure (10{sup {minus}3}, 10{sup {minus}4} and 10{sup {minus}5} torr).

A scanningelectron microscope (SEM) calibrating approach based on non-linear minimization procedure is presented in this article. A part of this article has been published in IEEE International Conference on Robotics and Automation (ICRA), 2014. . Both the intrinsic parameters and the extrinsic parameters estimations are achieved simultaneously by minimizing the registration error. The proposed approach considers multi-images of a multi-scale calibration pattern view from different positions and orientations. Since the projection geometry of the scanningelectron microscope is different from that of a classical optical sensor, the perspective projection model and the parallel projection model are considered and compared with distortion models. Experiments are realized by varying the position and the orientation of a multi-scale chessboard calibration pattern from 300× to 10,000×. The experimental results show the efficiency and the accuracy of this approach.

Measuring picometre-scale shifts in the positions of individual atoms in materials provides new insight into the structure of surfaces, defects and interfaces that influence a broad variety of materials' behaviour. Here we demonstrate sub-picometre precision measurements of atom positions in aberration-corrected Z-contrast scanning transmission electron microscopy images based on the non-rigid registration and averaging of an image series. Non-rigid registration achieves five to seven times better precision than previous methods. Non-rigidly registered images of a silica-supported platinum nanocatalyst show pm-scale contraction of atoms at a (111)/(111) corner towards the particle centre and expansion of a flat (111) facet. Sub-picometre precision and standardless atom counting with <1 atom uncertainty in the same scanning transmission electron microscopy image provide new insight into the three-dimensional atomic structure of catalyst nanoparticle surfaces, which contain the active sites controlling catalytic reactions. PMID:24916914

Measuring picometre-scale shifts in the positions of individual atoms in materials provides new insight into the structure of surfaces, defects and interfaces that influence a broad variety of materials’ behaviour. Here we demonstrate sub-picometre precision measurements of atom positions in aberration-corrected Z-contrast scanning transmission electron microscopy images based on the non-rigid registration and averaging of an image series. Non-rigid registration achieves five to seven times better precision than previous methods. Non-rigidly registered images of a silica-supported platinum nanocatalyst show pm-scale contraction of atoms at a ()/() corner towards the particle centre and expansion of a flat () facet. Sub-picometre precision and standardless atom counting with <1 atom uncertainty in the same scanning transmission electron microscopy image provide new insight into the three-dimensional atomic structure of catalyst nanoparticle surfaces, which contain the active sites controlling catalytic reactions.

The authors report on a macroscopic and microscopic study of human mandible bone lesions achieved by a single-blade knife and a hatchet. The aim of this work was to complete the previous data (scanningelectron microscopy analysis of bone lesions made by a single-blade knife and a hatchet, on human femurs) and to compare the lesions of the femur with those of the mandible. The results indicate that the mandible is a more fragile bone, but the features observed on the mandible are quite similar to those previously observed on the femur. This work spells out the main scanningelectron microscopy characteristics of sharp (bone cutting) and blunt (exerting a pressure on the bone) mechanisms on human bone. Weapon characteristics serve to explain all of these features. PMID:20890172

An add-on unit was developed that allows the cleaning of scanning tunneling microscope tips by electron beam annealing even if they cannot be disconnected from the piezo scanner in situ. The whole scanner tip combination, which is attached to a linear motion stage, is subjected to a pulsed annealing treatment. The heat impact is focused on the outermost tip by sticking the tip through a hole in a grounded Mo screening plate with the cathode mounted on the opposite side. Tungsten tips attached to the scanner of the Omicron ultrahigh vacuum Multiscan Lab were annealed to achieve atomic resolution of ultrahigh vacuum cleaved GaAs (110) faces. A highly doped superlattice package grown on semi-insulating GaAs was also able to be investigated on the cleaved (110) face due to the ability of exact tip positioning with a scanningelectron microscope.

Over the past few decades, numerous studies have been done on the freeze-drying of biological materials from a physical, chemical and biological point of view. Morphological observation of the freeze-drying process of specimens, however, has been tried by only a few investigators. In those studies, thin-layered aqueous specimens, which were sandwiched between two cover slips, were mostly observed with an optical microscope. For ultrastructural and stereoscopic observation, the scanningelectron microscope has a great advantage, unlike that of the optical microscope. A specially designed cryo-scanningelectron microscope, employed in the present study, made it possible to observe the freezing patterns of the specimens and also the sublimation process of ice in frozen specimens under vacuum. With this specially designed microscope, shrinkage of some specimens due to dehydration during the freeze-drying process was revealed and the extent of such shrinkage was quantitatively determined. PMID:1036327

Here, we report reproducible and accurate measurement of crystallographic parameters using scanning transmission electron microscopy. This is made possible by removing drift and residual scan distortion. We demonstrate real-space lattice parameter measurements with <0.1% error for complex-layered chalcogenides Bi2Te3, Bi2Se3, and a Bi2Te2.7Se0.3 nanostructured alloy. Pairing the technique with atomic resolution spectroscopy, we connect local structure with chemistry and bonding. Combining these results with density functional theory, we show that the incorporation of Se into Bi2Te3 causes charge redistribution that anomalously increases the van der Waals gap between building blocks of the layered structure. The results show that atomic resolution imaging with electrons can accurately and robustly quantify crystallography at the nanoscale. PMID:26169835

The ability to correct the aberrations of the probe-forming lens in the scanning transmission electron microscope provides not only a significant improvement in transverse resolution but in addition brings depth resolution at the nanometer scale. Aberration correction therefore opens up the possibility of 3D imaging by optical sectioning. Here we develop a definition for the depth resolution for scanning transmission electron microscope depth sectioning and present initial results from this method. Objects such as catalytic metal clusters and single atoms on various support materials are imaged in three dimensions with a resolution of several nanometers. Effective focal depth is determined by statistical analysis and the contributing factors are discussed. Finally, current challenges and future capabilities available through new instruments are discussed.

This article traces the important milestones in the development of high-resolution, field-emission, scanningelectron microscopes (SEM). Such instruments are now capable of producing images of the surfaces of biological specimens that rival, in terms of resolution and contrast, those produced by conventional transmission electron microscopy (TEM). Even though one of the first instruments to produce a useful transmission electron microscope image was, in fact, an early scanning microscope, TEM reached its full potential for biological imaging almost 30 years sooner than did SEM. The main reason for this slow rate of development is the dependence of any scanning technique on source brightness. The only suitable electron source was the field-emission source, originally developed in the 1930's. Making this into a stable and reliable electron source for microscopy required many technical barriers to be overcome. An additional delay may have been caused by the great success that attended the introduction of early SEM instruments. These instruments which employed heated, tungsten hairpin cathodes, were inexpensive and reliable, but they that were also far from optimal in terms of optical performance. Their market success may have engendered the sense of inertia and complacency that further delayed the introduction of low aberrations objective lenses and field-emission sources for almost 20 years after they were first introduced to electron microscopy. In addition, the fact that these early SEMs accustomed users to operating with a much higher beam voltage than was either necessary or wise, lead many to assume that the SEM was incapable of producing high-resolution images of biological surfaces. This left them open to fascination with newer ahd slower techniques that, on balance, were less suitable than optimized SEM for most of their imaging needs. In parallel to these developments in instrumentation, major improvements were also made in the way that the specimen surface

We use focused ion beam nanofabrication to manufacture forked diffraction gratings capable of producing electron beams with helical wavefronts and orbital angular momentum (OAM). A vast number of unique beam modes carrying OAM can be produced through manipulation of grating fork number or position. Generally these gratings are milled such that they produce a phase shift in the beam and are used with high energy electrons (300keV) in a TEM to investigate the quantum or magnetic properties of the electron or image magnetic materials. Our latest work focuses on manufacturing sub-100-nm pitch binary transmission gratings that produce only an amplitude modulation, which opens up imaging capability to lower energy electrons (5-30 keV) and thus expands their use to a wider range of commercially available SEMs. We use these amplitude gratings to show the relationship between the number/position of forks and OAM inherited by the beam. This work could lead to advances in imaging capability, and also creates a widely accessible and scalable demonstration of the quantum properties of the electron which can be leveraged by any science program with SEM access.

This case report provided a unique opportunity to investigate the extent of microbiota infiltration on the oxidized implant surface that has been compromised by peri-implantitis. Scanningelectron microscopic analysis confirmed the etiologic role of the bacteria on the loss of supporting structure and the difficulty in complete removal of bacterial infiltration on the implant surface. This case report emphasizes the need to perform definitive surface decontamination on failing dental implants prior to a regeneration procedure. PMID:27333005

Scanningelectron and light microscopic observations showed that egg hatching in Anopheles albimanus Wiedemann is aided by a chisel-shaped spine. This hatching tooth is surrounded by a thin flexible membrane fixed to a groove in the head of the larvae. Increased intracranial pressure may force the spine against the egg shell until a fissure is produced. Further opening of the egg is achieved by movements of the head and the entire body of the larva. PMID:1404271

Bonding dental amalgam to tooth reduces the occurrence of marginal leakage, fracture and sensitivity. However, most studies of amalgam bonding have made use of resin cements and the conventional three-bottle bonding agents. In this study, a newer, single-bottle bonding agent was used to bond amalgam both to dentin and enamel. Interfaces of bonded amalgam and unbonded amalgam were observed under the scanningelectron microscope. PMID:13677864

A scanningelectron microscope study of a fine-grained, pin, Ca-rich inclusion from the Allende meteorite has revealed strong evidence for direct condensation of its constituent minerals from a vapor. This observation extends to the alkali-bearing phases in addition to the Ca-, Al-silicates and suggests that the feldspathoids as well as the refractory silicates are solar nebular condensates.

Scanningelectron microscopy was used in studying the morphology and cathodoluminescence of lunar regolith particles. Surface and structure of two groups of particles are differentiated: (1) Crystalline with well defined facets and spalling surfaces, which are grains of minerals and rock fragments: and (2) amorphous, fused, and partially or entirely glazed particles. Local melting of particles and the round openings on their surfaces are attributed to secondary influence on the regolith of factors of lunar weathering and above all micrometeoric impacts.

The corneal endothelium is essential for the maintenance of the corneal transparency. The aim of this study was to examine the morphology of the endothelial surface and perform morphometric analysis of the normal corneal endothelial cells of the Magellanic penguin (Spheniscus magellanicus) using scanningelectron microscopy. The present work demonstrates that the corneal endothelium of the Magellanic penguin is similar to those described in other vertebrates. PMID:17312730

This article reports the use of the scanning electrochemical microscope (SECM) to investigate the electronic properties of Langmuir monolayers of alkane thiol protected gold nanocrystals (NCs). A substantial increase in monolayer conductivity upon mechanical compression of the Au NC monolayer is reported for the first time. This may be the room temperature signature of the insulator to metal transition previously reported for comparable silver NC monolayers. Factors influencing the conductivity of the monolayer NC array are discussed. PMID:15174884

A miniature, multi-channel, electronicallyscanned pressure measuring device uses electrostatically bonded silicon dies in a multi-element array. These dies are bonded at specific sites on a glass, pre-patterned substrate. Thermal data is multiplexed and recorded on each individual pressure measuring diaphragm. The device functions in a cryogenic environment without the need of heaters to keep the sensor at constant temperatures.

We characterized the structures of metal resists used in EUV lithography by low-voltage aberration-corrected scanning transmission electron microscopy (STEM) combined with electron energy-loss spectroscopy (EELS). This study presents the first atomic-level observation of resist components in resist film. The structures of metal (zirconium or titanium) oxide cores are unambiguously identified, and the local elemental distribution in the resist film is obtained. The initial size of zirconium oxide cores is well maintained in the resist film. However, titanium oxide cores tend to aggregate to form an indefinite structure. The spatial distribution of metal cores may influence lithographic characteristics.

A central focus of biological research is understanding the structure/function relationship of macromolecular protein complexes. Yet conventional transmission electron microscopy techniques are limited to static observations. Here we present the first direct images of purified macromolecular protein complexes using in situ liquid scanning transmission electron microscopy. Our results establish the capability of this technique for visualizing the interface between biology and nanotechnology with high fidelity while also probing the interactions of biomolecules within solution. This method represents an important advancement towards allowing future high-resolution observations of biological processes and conformational dynamics in real-time.

A successful diagnostic technique was developed using a scanningelectron microscope (SEM) as a precision tool to determine ionization effects in integrated circuits. Previous SEM methods radiated the entire semiconductor chip or major areas. The large area exposure methods do not reveal the exact components which are sensitive to radiation. To locate these sensitive components a new method was developed, which consisted in successively irradiating selected components on the device chip with equal doses of electrons /10 to the 6th rad (Si)/, while the whole device was subjected to representative bias conditions. A suitable device parameter was measured in situ after each successive irradiation with the beam off.

Preparation of suitable silicon (111) wafers in weakly alkaline HF solutions results in the formation of atomically flat, hydrogen-terminated surfaces. Under high-vacuum conditions, the scanning tunneling microscope has been employed to selectively desorb the passivating hydrogen from nanometer-sized surface regions. The hydrogen depassivation process is studied as a function of current and applied bias voltage, voltage polarity, and exposure time to incident electrons either on individual surface locations or by varying the speed of tip motion to control the electron dose. The experimental findings are interpreted in terms of two distinct desorption mechanisms and the respective desorption yields are specified. {copyright} {ital 1996 American Vacuum Society}

Accurate measurement of the strain field in the channels of transistor arrays is critical for strain engineering in modern electronic devices. We applied atomic-resolution high-angle annular dark-field scanning transmission electron microscopy to quantitative measurement of the strain field in transistor arrays. The quantitative strain profile over 20 transistors was obtained with high reliability and a precision of 0.1%. The strain field was found to form homogeneously in the channels of the transistor arrays. Furthermore, strain relaxation due to the thin foil effect was quantitatively investigated for thicknesses of 35 to 275 nm.

A gas microinjector system was set up in an environmental scanningelectron microscope (ESEM) to create an oxygen atmosphere around the alumina samples for the charging compensation under a pressure between 2 x 10(-5) Pa approximately 2 x 10(-2) Pa. At low pressures, the skirt effect of the electron scattering can be degraded, which results in improvement of the imaging contrast and increase of the signal/noise ratio. The sample current (I(SC)) and the Duane-Hunt limit were measured to evaluate the charging effect. PMID:17063769

The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals. PMID:26923483

We describe the use of electron channeling contrast imaging in the scanningelectron microscope to rapidly and reliably image and identify threading dislocations (TDs) in materials with the wurtzite crystal structure. In electron channeling contrast imaging, vertical TDs are revealed as spots with black-white contrast. We have developed a simple geometric procedure which exploits the differences observed in the direction of this black-white contrast for screw, edge, and mixed dislocations for two electron channeling contrast images acquired from two symmetrically equivalent crystal planes whose g vectors are at 120° to each other. Our approach allows unambiguous identification of all TDs without the need to compare results with dynamical simulations of channeling contrast.

The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.

Several reviews have highlighted a number of applications of scanningelectron acoustic microscopy (SEAM) to metals and semiconductors which show that SEAM can provide new information on surface and near-surface features of such materials, but there have been few studies attempting to determine the capabilities of SEAM for characterizing ceramic materials. We have recently observed image contrast in SEAM from residual stress fields induced in brittle materials by Vickers indentations that is strongly dependent on the electron beam chopping frequency. We have also recently developed a three-dimensional mathematical model of signal generation and contrast in SEAM, appropriate to the brittle materials studied, that we use as a starting point in this paper for modeling the effect of residual stress fields on the generated electron acoustic signal. The influence of the electron beam chopping frequency is also considered under restrictive assumptions.

The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals. PMID:26923483

Single-wall carbon nanotubes, seamless cylindrical molecules formed from a graphene sheet, are either conducting or semiconducting, depending on the particular "wrapping vector" that defines the waist of the tube. Scanning tunneling microscopy experiments have tested this idea by simultaneously measuring a tube's lattice structure and electronic properties. Here we present a series of STM images of single-wall carbon nanotubes with a strikingly rich set of superstructures. The observed patterns can be understood as due to interference between propagating electron waves that are reflected from defects on the tube walls and ends, or as intrinsic to states propagating on semiconducting tubes. The measured broken symmetries can be used to directly probe electronic backscattering on the tube and provide a key element in the understanding of low-energy electron transport on these structures.

Both scanningelectron microscopes (SEM) and helium ion microscopes (HeIM) are based on the same principle of a charged particle beam scanning across the surface and generating secondary electrons (SEs) to form images. However, there is a pronounced difference in the energy spectra of the emitted secondary electrons emitted as result of electron or helium ion impact. We have previously presented evidence that this also translates to differences in the information depth through the analysis of dopant contrast in doped silicon structures in both SEM and HeIM. Here, it is now shown how secondary electron emission spectra (SES) and their relation to depth of origin of SE can be experimentally exploited through the use of energy filtering (EF) in low voltage SEM (LV-SEM) to access bulk information from surfaces covered by damage or contamination layers. From the current understanding of the SES in HeIM it is not expected that EF will be as effective in HeIM but an alternative that can be used for some materials to access bulk information is presented.

Background: Forensic dental identification of victims involved in fire accidents is often a complex and challenging endeavor. Knowledge of the charred human dentition and residues of restorative material can help in the recognition of bodies burned beyond recognition. Aim: To observe the effects of predetermined temperatures on healthy unrestored teeth and different restorative materials in restored teeth, by scanningelectron microscope, for the purpose of identification. Materials and Methods: The study was conducted on 135 extracted teeth, which were divided into four groups. Group 1-healthy unrestored teeth, group 2-teeth restored with all ceramic crowns, group 3-teeth restored with class I composite resin and group 4-teeth restored with class I glass ionomer cement (GIC). Results: The scanningelectron microscope is useful in the analysis of burned teeth, as it gives fine structural details, requires only a small sample and does not destroy the already fragile specimen. Conclusion: Scanningelectron microscope can be a useful tool for the characterization and study of severely burnt teeth for victim identification. PMID:24959034

Summary Serial block‐face scanningelectron microscopy (SBEM) is becoming increasingly popular for a wide range of applications in many disciplines from biology to material sciences. This review focuses on applications for circuit reconstruction in neuroscience, which is one of the major driving forces advancing SBEM. Neuronal circuit reconstruction poses exceptional challenges to volume EM in terms of resolution, field of view, acquisition time and sample preparation. Mapping the connections between neurons in the brain is crucial for understanding information flow and information processing in the brain. However, information on the connectivity between hundreds or even thousands of neurons densely packed in neuronal microcircuits is still largely missing. Volume EM techniques such as serial section TEM, automated tape‐collecting ultramicrotome, focused ion‐beam scanningelectron microscopy and SBEM (microtome serial block‐face scanningelectron microscopy) are the techniques that provide sufficient resolution to resolve ultrastructural details such as synapses and provides sufficient field of view for dense reconstruction of neuronal circuits. While volume EM techniques are advancing, they are generating large data sets on the terabyte scale that require new image processing workflows and analysis tools. In this review, we present the recent advances in SBEM for circuit reconstruction in neuroscience and an overview of existing image processing and analysis pipelines. PMID:25907464

We have developed spin-polarized scanningelectron microscopy (spin SEM) with a 5-nm resolution. The secondary electron optics is very important, as it needs to transfer a sufficient number of secondary electrons to the spin polarimeter, due to the low efficiency of the polarimeter. The optics was designed using a three-dimensional (3D) simulation program of the secondary electron trajectories, and it achieves highly efficient collection and transport of the secondary electrons even though the distance between the sample and the objective lens exit of the electron gun remains short. Moreover, the designed optics enables us to obtain clear SEM images in the spin SEM measurement and to precisely adjust the probe beam shape. These functions lead to images with high spatial resolution and sufficient signal-to-noise (S/N) ratios. This optics has been installed in an ultra-high vacuum (UHV) spin SEM chamber with a Schottky-type electron gun for the probe electron beam. We observed recorded bits on a perpendicular magnetic recording medium and visualized small irregularities in the bit shapes around the track edges and bit boundaries. The high resolution of 5 nm was demonstrated by observing the smallest domain composed by a single grain in the recording medium. PMID:19840986

High quality of secondary electron (SE) images, taken at useful magnifications of 100,000 to 200,000, require new signal generation and collection methods and new metal coating procedures. High quality is defined as the condition under which image contrast describes accurately the topographic features of the specimen in a size range that approximates the beam diameter. Such high resolution contrasts are produced by the SE (SE-I) generated by a small electron probe on the specimen surface. Tobacco mosiac virus and ferritin molecules deposited on bulk substrates were introduced as test specimens to check the image quality obtained. The SE-I signal contrast could be imaged when SE (SE-III), produced by backscattered electrons (BSE) at the pole piece of the final lens, were eliminated with an electron absorption device attached to the pole piece. This signal collection procedure will be referred to as "Secondary Electron-I Image" (SE-I image) mode. In addition to the SE-III, BSE generate SE-II in the specimen itself. On specimens deposited on bulk gold or platinum, and coated with the same metals SE-II produced a microroughness contrast that limited particle resolution in the SE-I image mode to approximately 10 nm. Reduction of SE-II and enrichment of the signal in SE-I was achieved by using continuous fine crystalline coatings of tantalum, niobium and chromium. By applying these metals in films of approximately 2.0 nm thickness, the SE-I contrast generation was found to be indepedent of the atomic number of the metal. Edge sharpness was improved when the specimens were coated with low atomic number metals. Under these conditions, the quality of images obtained in SE-I image mode equals that of images obtained in TEM from identically coated specimens and was limited only by the size of the topographic details, beam diameter and beam current. PMID:7184136

The highly energetic electron beam (e-beam) in a scanning transmission electron microscope (STEM) can induce local changes in the state of matter, ranging from knock-on and atomic movement, to amorphization/crystallization, and to localized chemical/electrochemical reactions. To date, fundamental studies of e-beam induced phenomena and practical applications have been limited by conventional STEM e-beam rastering modes that allow only for uniform e-beam exposures. Here, an automated liquid phase nanolithography method has been developed that enables the direct writing of nanometer scaled features within microfabricated liquid cells. An external e-beam control system, connected to the scan coils of an aberration-corrected STEM, is used to precisely control the position, dwell time, and scan rate of a sub-nanometer STEM probe. Site-specific locations in a sealed liquid cell containing an aqueous solution of H2PdCl4 are irradiated to deposit palladium nanocrystals onto silicon nitride membranes in a highly controlled manner. The threshold electron dose required for the radiolytic deposition of metallic palladium has been determined, the influence of electron dose on the nanolithographically patterned feature size and morphology is explored, and a feedback-controlled monitoring method for active control of the nanofabricated structures through STEM detector signal monitoring is proposed. This approach enables fundamental studies of electron beam induced interactions with matter in liquid cells and opens new pathways to fabricate nanostructures with tailored architectures and chemistries via shape-controlled nanolithographic patterning from liquid-phase precursors. PMID:27510435

Interfacial science has received much attention recently based on the development of state-of-the-art analytical tools that can create and manipulate the charge, spin, orbital, and lattice degrees of freedom at interfaces. Motivated by the importance of nanoscale interfacial science that governs device operation, we present a technique to probe the electronic characteristics of heterointerfaces with atomic resolution. In this work, the interfacial characteristics of heteroepitaxial structures are investigated and the fundamental mechanisms that pertain in these systems are elucidated through cross-sectional scanning tunneling microscopy (XSTM). The XSTM technique is employed here to directly observe epitaxial interfacial structures and probe local electronic properties with atomic-level capability. Scanning tunneling microscopy and spectroscopy experiments with atomic precision provide insight into the origin and spatial distribution of electronic properties across heterointerfaces. The first part of this report provides a brief description of the cleavage technique and spectroscopy analysis in XSTM measurements. The second part addresses interfacial electronic structures of several model heterostructures in current condensed matter research using XSTM. Topics to be discussed include high-κ's/III-V's semiconductors, polymer heterojunctions, and complex oxide heterostructures, which are all material systems whose investigation using this technique is expected to benefit the research community. Finally, practical aspects and perspectives of using XSTM in interface science are presented. PMID:26202580

A thermoelectric cooling / heating setup for commercial Quantomix QX WETSEM scanningelectron microscopy environmental cells was designed and tested. This addition allows extending ambient pressure in situ studies to be conducted in a wide temperature range both in liquid and gaseous environments. Instead of cooling/heating the entire body of QX-WETCELL, ultrathin polyimide electron transparent membrane window supported by metal mesh on the top of the cell has been used as an agent for heat transfer to/ from the Pelltier element. A butterfly wing of Morph sulkowskyi has been used as a model object in the QX-WETCELL's chamber due to its unique micro/nanostructure and peculiar wettability behavior. The dynamics of the water desorption, condensation and freezing processes were observed complementary using both optical microscopy and ScanningElectron Microscopy in vivo. The observations revel that the initial droplet formation were most likely taking place on the top of the wing ridges due to the waxy component of its surface. In addition, The SEM observation showed that the high intensity electron beam can heat the butterfly wing locally delaying the water condensation and freezing processes.

Interfacial science has received much attention recently based on the development of state-of-the-art analytical tools that can create and manipulate the charge, spin, orbital, and lattice degrees of freedom at interfaces. Motivated by the importance of nanoscale interfacial science that governs device operation, we present a technique to probe the electronic characteristics of heterointerfaces with atomic resolution. In this work, the interfacial characteristics of heteroepitaxial structures are investigated and the fundamental mechanisms that pertain in these systems are elucidated through cross-sectional scanning tunneling microscopy (XSTM). The XSTM technique is employed here to directly observe epitaxial interfacial structures and probe local electronic properties with atomic-level capability. Scanning tunneling microscopy and spectroscopy experiments with atomic precision provide insight into the origin and spatial distribution of electronic properties across heterointerfaces. The first part of this report provides a brief description of the cleavage technique and spectroscopy analysis in XSTM measurements. The second part addresses interfacial electronic structures of several model heterostructures in current condensed matter research using XSTM. Topics to be discussed include high-κ‘s/III-V’s semiconductors, polymer heterojunctions, and complex oxide heterostructures, which are all material systems whose investigation using this technique is expected to benefit the research community. Finally, practical aspects and perspectives of using XSTM in interface science are presented.

Low-vacuum scanningelectron microscopy (LV-SEM) has been developed which enables the observation of soft, moist, and electrically insulating materials without any pretreatment unlike conventional scanningelectron microscopy, in which samples must be solid, dry and usually electrically conductive. The purpose of this study was to assess the usefulness of LV-SEM for renal biopsy specimens. We analyzed 20 renal biopsy samples obtained for diagnostic purposes. The sections were stained with periodic acid methenamine silver to enhance the contrast, and subsequently examined by LV-SEM. LV-SEM showed a precise and fine structure of the glomerulus in both formalin fixed paraffin and glutaraldehyde-osmium tetroxide-fixed epoxy resin sections up to 10,000-fold magnification. The spike formation on the basement membrane was clearly observed in the membranous nephropathy samples. Similarly to transmission electron microscopy, electron dense deposits were observed in the epoxy resin sections of the IgA nephropathy and membranous nephropathy samples. LV-SEM could accurately show various glomerular lesions at high magnification after a simple and rapid processing of the samples. We consider that this is a novel and useful diagnostic tool for renal pathologies. PMID:22795691

When developing new nanoparticles for bio-applications, it is important to fully characterize the nanoparticle's behavior in biological systems. The most common techniques employed for mapping nanoparticles inside cells include transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). These techniques entail passing an electron beam through a thin specimen. STEM or TEM imaging is often used for the detection of nanoparticles inside cellular organelles. However, lengthy sample preparation is required (i.e., fixation, dehydration, drying, resin embedding, and cutting). In the present work, a new matrix (FTO glass) for biological samples was used and characterized by field emission scanningelectron microscopy (FE-SEM) to generate images comparable to those obtained by TEM. Using FE-SEM, nanoparticle images were acquired inside endo/lysosomes without disruption of the cellular shape. Furthermore, the initial steps of nanoparticle incorporation into the cells were captured. In addition, the conductive FTO glass endowed the sample with high stability under the required accelerating voltage. Owing to these features of the sample, further analyses could be performed (material contrast and energy-dispersive X-ray spectroscopy (EDS)), which confirmed the presence of nanoparticles inside the cells. The results showed that FE-SEM can enable detailed characterization of nanoparticles in endosomes without the need for contrast staining or metal coating of the sample. Images showing the intracellular distribution of nanoparticles together with cellular morphology can give important information on the biocompatibility and demonstrate the potential of nanoparticle utilization in medicine. PMID:25173605

A scanning transmission electron microscope (STEM) produces a convergent beam electron diffraction pattern at each position of a raster scan with a focused electron beam, but recording this information poses major challenges for gathering and storing such large data sets in a timely manner and with sufficient dynamic range. To investigate the crystalline structure of materials, a 16x16 analog pixel array detector (PAD) is used to replace the traditional detectors and retain the diffraction information at every STEM raster position. The PAD, unlike a charge-coupled device (CCD) or photomultiplier tube (PMT), directly images 120-200keV electrons with relatively little radiation damage, exhibits no afterglow and limits crosstalk between adjacent pixels. Traditional STEM imaging modes can still be performed by the PAD with a 1.1kHz frame rate, which allows post-acquisition control over imaging conditions and enables novel imaging techniques based on the retained crystalline information. Techniques for rapid, semi-automatic crystal grain segmentation with sub-nanometer resolution are described using cross-correlation, sub-region integration, and other post-processing methods. PMID:19162398

Lateral profiles of the electron probe of scanning transmission electron microscopy (STEM) were simulated at different vertical positions in a micrometers-thick carbon sample. The simulations were carried out using the Monte Carlo method in CASINO software. A model was developed to fit the probe profiles. The model consisted of the sum of a Gaussian function describing the central peak of the profile and two exponential decay functions describing the tail of the profile. Calculations were performed to investigate the fraction of unscattered electrons as a function of the vertical position of the probe in the sample. Line scans were also simulated over gold nanoparticles at the bottom of a carbon film to calculate the achievable resolution as a function of the sample thickness and the number of electrons. The resolution was shown to be noise limited for film thicknesses less than 1 μm. Probe broadening limited the resolution for thicker films. The validity of the simulation method was verified by comparing simulated data with experimental data. The simulation method can be used as quantitative method to predict STEM performance or to interpret STEM images of thick specimens. PMID:22564444

The nanoscale optical response of surface plasmons in three-dimensional metallic nanostructures plays an important role in many nanotechnology applications, where precise spatial and spectral characteristics of plasmonic elements control device performance. Electron energy loss spectroscopy (EELS) and cathodoluminescence (CL) within a scanning transmission electron microscope have proven to be valuable tools for studying plasmonics at the nanoscale. Each technique has been used separately, producing three-dimensional reconstructions through tomography, often aided by simulations for complete characterization. Here we demonstrate that the complementary nature of the two techniques, namely that EELS probes beam-induced electronic excitations while CL probes radiative decay, allows us to directly obtain a spatially- and spectrally-resolved picture of the plasmonic characteristics of nanostructures in three dimensions. The approach enables nanoparticle-by-nanoparticle plasmonic analysis in three dimensions to aid in the design of diverse nanoplasmonic applications.

The nanoscale optical response of surface plasmons in three-dimensional metallic nanostructures plays an important role in many nanotechnology applications, where precise spatial and spectral characteristics of plasmonic elements control device performance. Electron energy loss spectroscopy (EELS) and cathodoluminescence (CL) within a scanning transmission electron microscope have proven to be valuable tools for studying plasmonics at the nanoscale. Each technique has been used separately, producing three-dimensional reconstructions through tomography, often aided by simulations for complete characterization. Here we demonstrate that the complementary nature of the two techniques, namely that EELS probes beam-induced electronic excitations while CL probes radiative decay, allows us to directly obtain a spatially- and spectrally-resolved picture of the plasmonic characteristics of nanostructures in three dimensions. The approach enables nanoparticle-by-nanoparticle plasmonic analysis in three dimensions to aid in the design of diverse nanoplasmonic applications. PMID:26934391

A new area detector for atomic-resolution scanning transmission electron microscopy (STEM) is developed and tested. The circular detector is divided into 16 segments which are individually optically coupled with photomultiplier tubes. Thus, 16 atomic-resolution STEM images which are sensitive to the spatial distribution of scattered electrons on the detector plane can be simultaneously obtained. This new detector can be potentially used not only for the simultaneous formation of common bright-field, low-angle annular dark-field and high-angle annular dark-field images, but also for the quantification of images by detecting the full range of scattered electrons and even for exploring novel atomic-resolution imaging modes by post-processing combination of the individual images. PMID:20406732

The recent interest in size-dependent deformation of micro- and nanoscale materials has paralleled both technological miniaturization and advancements in imaging and small-scale mechanical testing methods. Here we describe a quantitative in situ nanomechanical testing approach adapted to a dual-beam focused ion beam and scanningelectron microscope. A transducer based on a three-plate capacitor system is used for high-fidelity force and displacement measurements. Specimen manipulation, transfer, and alignment are performed using a manipulator, independently controlled positioners, and the focused ion beam. Gripping of specimens is achieved using electron-beam assisted Pt-organic deposition. Local strain measurements are obtained using digital image correlation of electron images taken during testing. Examples showing results for tensile testing of single-crystalline metallic nanowires and compression of nanoporous Au pillars will be presented in the context of size effects on mechanical behavior and highlight some of the challenges of conducting nanomechanical testing in vacuum environments.

Results of detectable distance calculations for a visual navigation system based on a scanning semiconductor laser with electronic pumping (SSLEP) are presented. A semiconductor crystal in the laser is pumped with an electron beam, which is scanned across the crystal in the television-frame scan mode. The navigation system forms three orientation sectors with radiation wavelengths λ=0.52, 0.57, and 0.63 μm. Herein, calculations of energetic characteristics of output radiation are performed for the navigation system described above. The calculations were performed using the Range software package, which considers microphysical and optical characteristics of aerosol and observation path geometry for the case of coastal environment. Finally, comparison of results of the calculations with data obtained in marine and flight experiments is presented. It is demonstrated that minor discrepancies between calculated and measured values of detectable distance are observed in the coastal haze at lower values of meteorological visibility range S(m). As S(m) increases, the discrepancies become significant. PMID:21743551

A two-stage model is presented to describe alloy element evaporation rates from molten metal due to transient local heating by an electron beam. The first stage is a simulation of transient phenomena near the melt surface due to periodic heating by a scanning beam, the output of which is the relationship between operating parameters, surface temperature, and evaporation rate. At high scan rates, this can be done using a simple one-dimensional heat transfer model of the surface layer; at lower scan rates, a more complex three-dimensional model with fluid flow and periodic boundary conditions is necessary. The second stage couples this evaporation-surface temperature relationship with a larger steady state heat transfer and fluid flow model of an entire melting hearth or mold, in order to calculate local and total evaporation rates. Predictions are compared with experimental results from Sandia`s 310-kW electron beam melting furnace, in which evaporation rates and vapor compositions were studied in pure titanium and Ti-6%Al-4%V alloy. Evaporation rates were estimated from rate of condensation on a substrate held over the hearth, and were characterized as a function of beam power (10{sup {minus}3}, 10{sup {minus}4} and 10{sup {minus}5} torr).

The genus Cichlidogyrus (Monogenea: Ancyrocephalidae) includes more than 90 species, most of which are gill parasites of African cichlid fishes. Cichlidogyrus has been studied extensively in recent years, but scanningelectron microscope (SEM) investigations of the isolated hard parts have not yet been undertaken. In this paper, we describe a method for isolating and scanning the sclerites of individual Cichlidogyrus worms. Twenty-year-old, formol-fixed specimens of Cichlidogyrus casuarinus were subjected to proteinase K digestion in order to release the sclerites from the surrounding soft tissues. SEM micrographs of the haptoral sclerites and the male copulatory organ are presented. The ability to digest formol-fixed specimens makes this method a useful tool for the study of historical museum collections. PMID:25828814

A fossil dinosaur bone, 80 million years old, was subjected to investigation in the scanning microscope. The bone surfaces to be examined were prepared with appropritely modified methods used in the technique of replication in transmission electron microscopy. In the scanning microscope pictures of vascular canals were obtained. The walls of these canals were shown to be formed of collagen fibrils. Moreover, it was demonstrated that the internal surface of the canal wall is made up of bundles of collagen fibrils which run obliquely, corkscrewwise, and in the form of plexus to the long axis of tke canal; Besides, osteocytes of the dinosaur bone were isolated and pictures of their spatial structure together with characteristic points of departure of processes from the cell body were obtained. PMID:1224770

We show, for the first time to our knowledge, how wavelength-scanning interferometry can be used to measure depth-resolved displacement fields through semitransparent scattering surfaces. Temporal sequences of speckle interferograms are recorded while the wavelength of the laser is tuned at a constant rate. Fourier transformation of the resultant three-dimensional (3-D) intensity distribution along the time axis reconstructs the scattering potential within the medium, and changes in the 3-D phase distribution measured between two separate scans provide the out-of-plane component of the 3-D displacement field. The principle of the technique is explained in detail and illustrated with a proof-of-principle experiment involving two independently tilted semitransparent scattering surfaces. Results are validated by standard two-beam electronic speckle pattern interferometry.

A particularly simple conversion of a scanning Auger system for ESD ion energy distributions and scanning ESD has been developed. This approach combines the advantages of the small spot-size electron guns and mapping systems developed for SAM with the capability of ESD for the detection of hydrogen. Our intended use for the device is detection and mapping of surface concentrations of hydrogen on metals. The characteristics of SESD are illustrated with the preliminary results of an investigation into the ESD properties of hydrogenic adsorbates on Nb. It is shown that the ESDIED exhibit distinct differences indicative of the surface preparation, and that the ESD ion angular distributions have an effect on the observed contrast relationships in SESD.

Highlights: Black-Right-Pointing-Pointer Mycoplasma mobile was observed in buffer with the Atmospheric ScanningElectron Microscope. Black-Right-Pointing-Pointer Characteristic protein localizations were visualized using immuno-labeling. Black-Right-Pointing-Pointer M. mobile attached to sialic acid on the SiN film surface within minutes. Black-Right-Pointing-Pointer Cells were observed at low concentrations. Black-Right-Pointing-Pointer ASEM should promote study and early-stage diagnosis of mycoplasma. -- Abstract: Mycoplasma is a genus of bacterial pathogen that causes disease in vertebrates. In humans, the species Mycoplasma pneumoniae causes 15% or more of community-acquired pneumonia. Because this bacterium is tiny, corresponding in size to a large virus, diagnosis using optical microscopy is not easy. In current methods, chest X-rays are usually the first action, followed by serology, PCR amplification, and/or culture, but all of these are particularly difficult at an early stage of the disease. Using Mycoplasma mobile as a model species, we directly observed mycoplasma in buffer with the newly developed Atmospheric ScanningElectron Microscope (ASEM). This microscope features an open sample dish with a pressure-resistant thin film window in its base, through which the SEM beam scans samples in solution, from below. Because of its 2-3 {mu}m-deep scanning capability, it can observe the whole internal structure of mycoplasma cells stained with metal solutions. Characteristic protein localizations were visualized using immuno-labeling. Cells were observed at low concentrations, because suspended cells concentrate in the observable zone by attaching to sialic acid on the silicon nitride (SiN) film surface within minutes. These results suggest the applicability of the ASEM for the study of mycoplasmas as well as for early-stage mycoplasma infection diagnosis.

Large-scale 2D electron microscopy (EM), or nanotomy, is the tissue-wide application of nanoscale resolution electron microscopy. Others and we previously applied large scale EM to human skin pancreatic islets, tissue culture and whole zebrafish larvae1-7. Here we describe a universally applicable method for tissue-scale scanning EM for unbiased detection of sub-cellular and molecular features. Nanotomy was applied to investigate the healthy and a neurodegenerative zebrafish brain. Our method is based on standardized EM sample preparation protocols: Fixation with glutaraldehyde and osmium, followed by epoxy-resin embedding, ultrathin sectioning and mounting of ultrathin-sections on one-hole grids, followed by post staining with uranyl and lead. Large-scale 2D EM mosaic images are acquired using a scanning EM connected to an external large area scan generator using scanning transmission EM (STEM). Large scale EM images are typically ~ 5 - 50 G pixels in size, and best viewed using zoomable HTML files, which can be opened in any web browser, similar to online geographical HTML maps. This method can be applied to (human) tissue, cross sections of whole animals as well as tissue culture1-5. Here, zebrafish brains were analyzed in a non-invasive neuronal ablation model. We visualize within a single dataset tissue, cellular and subcellular changes which can be quantified in various cell types including neurons and microglia, the brain's macrophages. In addition, nanotomy facilitates the correlation of EM with light microscopy (CLEM)8 on the same tissue, as large surface areas previously imaged using fluorescent microscopy, can subsequently be subjected to large area EM, resulting in the nano-anatomy (nanotomy) of tissues. In all, nanotomy allows unbiased detection of features at EM level in a tissue-wide quantifiable manner. PMID:27285162

Large-scale 2D electron microscopy (EM), or nanotomy, is the tissue-wide application of nanoscale resolution electron microscopy. Others and we previously applied large scale EM to human skin pancreatic islets, tissue culture and whole zebrafish larvae(1-7). Here we describe a universally applicable method for tissue-scale scanning EM for unbiased detection of sub-cellular and molecular features. Nanotomy was applied to investigate the healthy and a neurodegenerative zebrafish brain. Our method is based on standardized EM sample preparation protocols: Fixation with glutaraldehyde and osmium, followed by epoxy-resin embedding, ultrathin sectioning and mounting of ultrathin-sections on one-hole grids, followed by post staining with uranyl and lead. Large-scale 2D EM mosaic images are acquired using a scanning EM connected to an external large area scan generator using scanning transmission EM (STEM). Large scale EM images are typically ~ 5 - 50 G pixels in size, and best viewed using zoomable HTML files, which can be opened in any web browser, similar to online geographical HTML maps. This method can be applied to (human) tissue, cross sections of whole animals as well as tissue culture(1-5). Here, zebrafish brains were analyzed in a non-invasive neuronal ablation model. We visualize within a single dataset tissue, cellular and subcellular changes which can be quantified in various cell types including neurons and microglia, the brain's macrophages. In addition, nanotomy facilitates the correlation of EM with light microscopy (CLEM)(8) on the same tissue, as large surface areas previously imaged using fluorescent microscopy, can subsequently be subjected to large area EM, resulting in the nano-anatomy (nanotomy) of tissues. In all, nanotomy allows unbiased detection of features at EM level in a tissue-wide quantifiable manner. PMID:27285162

The ampullary segment of the mammalian oviduct provides suitable milieu for fertilization and development of zygote before implantation into uterus. It is, therefore, in the present study, the cyclic changes in the morphology of ampullary segment of goat oviduct were studied during follicular and luteal phases using scanning and transmission electron microscopy techniques. Topographical analysis revealed the presence of uniformly ciliated ampullary epithelia, concealing apical processes of non-ciliated cells along with bulbous secretory cells during follicular phase. The luteal phase was marked with decline in number of ciliated cells with increased occurrence of secretory cells. The ultrastructure analysis has demonstrated the presence of indented nuclear membrane, supranuclear cytoplasm, secretory granules, rough endoplasmic reticulum, large lipid droplets, apically located glycogen masses, oval shaped mitochondria in the secretory cells. The ciliated cells were characterized by the presence of elongated nuclei, abundant smooth endoplasmic reticulum, oval or spherical shaped mitochondria with crecentric cristae during follicular phase. However, in the luteal phase, secretory cells were possessing highly indented nucleus with diffused electron dense chromatin, hyaline nucleosol, increased number of lipid droplets. The ciliated cells had numerous fibrous granules and basal bodies. The parallel use of scanning and transmission electron microscopy techniques has enabled us to examine the cyclic and hormone dependent changes occurring in the topography and fine structure of epithelium of ampullary segment and its cells during different reproductive phases that will be great help in understanding major bottle neck that limits success rate in vitro fertilization and embryo transfer technology. PMID:25491952

Scanningelectron microscopes are some of the most versatile tools for imaging materials with nanometer resolution. However, images collected at high scan rates to increase throughput and avoid sample damage, suffer from low signalto- noise ratio (SNR) as a result of the Poisson distributed shot noise associated with the electron production and interaction with the surface imaged. The signal is further degraded by additive white Gaussian noise (AWGN) from the detection electronics. In this work, denoising frameworks are applied to this type of images, taking advantage of their sparsity character, along with a methodology for determining the AWGN. A variance stabilization technique is applied to the raw data followed by a patch-based denoising algorithm. Results are presented both for images with known levels of mixed Poisson-Gaussian noise, and for raw images. The quality of the image reconstruction is assessed based both on the PSNR as well as on measures specific to the application of the data collected. These include accurate identification of objects of interest and structural similarity. High-quality results are recovered from noisy observations collected at short dwell times that avoid sample damage.

The dissociation supernatant (DS) isolated by disaggregating Strongylocentrotus purpuratus blastulae in calcium- and magnesium-free seawater specifically promotes reaggregation of S. purpuratus blastula cells. The purpose of this study was to use scanningelectron microscopy to examine the gross morphology of aggregates formed in the presence of DS to see if it resembles adhesion in partially dissociated blastulae. A new reaggregation procedure developed here, using large volumes of cell suspension and a large diameter of rotation, was utilized to obtain sufficient quantities of aggregates for scanningelectron microscopy. The results indicate that aggregates formed in the presence of DS resemble partially dissociated intact embryos in terms of the direct cell-cell adhesion observed. DS did not cause aggregation to form as a result of the entrapment of cells in masses of extracellular material. These studies provide the groundwork for further studies using transmission electron microscopy to more precisely define the adhesive contacts made by cells in the presence of the putative adhesion molecules present in DS.

Scanning electrochemical microscopy (SECM) is a powerful new tool for studying chemical and biological processes. It records changes in faradaic current as a microelectrode ([less than equal]7 [mu]m in diameter) is moved across the surface of a sample. The current varies as a function of both distance from the surface and the surface's chemical and electrical properties. We used SECM to examine in vivo topography and photosynthetic electron transport of individual guard cells in Tradescantia fluminensis, to our knowledge the first such analysis for an intact plant. We measured surface topography at the micrometer level and concentration profiles of O2 evolved in photosynthetic electron transport. Comparison of topography and oxygen profiles above single stomatal complexes clearly showed photosynthetic electron transport in guard cells, as indicated by induction of O2 evolution by photosynthetically active radiation. SECM is unique in its ability to measure topography and chemical fluxes, combining some of the attributes of patch clamping with scanning tunneling microscopy. In this paper we suggest several questions in plant physiology that it might address. PMID:12223651

Fifty seven blocks of cartilage excised from the femoral condyles of 20 beagle dogs, and whole lower ends of 5 guinea-pig femora, were examined at -195 degrees (78 K), by scanningelectron microscopy. The unfixed tissue, taken into slushy nitrogen at -210 degrees (63 K), was not exposed to atmospheric air after quenching and remained fully hydrated throughout long periods of observation. Images susceptible to analysis were obtained from washed and from unwashed cartilage surfaces. Preliminary coating with gold or with aluminium, known to be possible without exposing cold cartilage surfaces to changes in temperature likely to cause water loss by sublimation, was valuable in minimising charging and in facilitating the recording of electron images at higher magnifications. Although examination was possible without coating, the resultant images were of low resolution. Microscopy revealed a pattern of secondary surface irregularities of tertiary elevations closely resembling those seen by the conventional scanningelectron microscopy of fixed, dehydrated hyaline cartilage. However, the pattern of tertiary surface structures was predominantly that of elevations, not of hollows. Quaternary surface ridges were common on the surfaces of excised dog cartilage blocks and were not seen on the surfaces of guinea-pig cartilage which remained on the femoral condyles. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 PMID:7024225

Carbon fullerenes are unusually structured molecules with robust mechanical and electronic properties. Their versatility is astounding; envisioned applications range from field emission displays to impregnated metal composites, battery storage media, and nanoelectronic devices. The combination of simple constituency, diverse behavior, and ease of fabrication makes these materials a cornerstone topic in current research. This thesis details scanning tunneling microscopy (STM) experiments investigating how carbon nanotube fullerenes interact with and couple to their local environment. Scanning tunneling microscopy continues to be a key method for characterizing fullerenes, particularly in regards to their electronic properties. The atomic scale nature of this technique makes it uniquely suited for observing individual molecules and determining correlations between locally measured electronic properties and the particular environment of the molecule. The primary subject of this study is single-wall carbon nanotubes (SWNTs), which were observed under various perturbative influences resulting in measurable changes in the electronic structure. Additionally, fullerene heterostructures formed by the encapsulation of C60 molecules within the hollow interiors of SWNTs were characterized for the first time with STM. These novel macromolecules (dubbed "peapods") demonstrate the potential for custom engineering the properties of fullerene materials. Measurements indicate that the properties of individual nanotubes depend sensitively on local interactions. In particular, pronounced changes in electronic behavior are observed in nanotubes exhibiting mechanical distortion, interacting with extrinsic materials (including other nanotubes), and possessing intrinsic defects in the atomic lattice. In fullerene peapods, while no discernable change in the atomic ordering of the encapsulating nanotubes was evident, the presence of interior C60 molecules has a dramatic effect on the

The dual beam scanningelectron microscope, equipped with both a focused ion- and scanningelectron- beam (FIB SEM) is a novel tool for the exploration of the subsurface structure of biological tissues. The FIB can remove a predetermined amount of material from a selected site to allow for subsurface exploration and when coupled with SEM or scanning ion- beam microscopy (SIM) could be suitable to examine the subsurface structure of bacterial biofilms on the leaf surface. The suitability of chemical and cryofixation was examined for use with the FIB SEM to examine bacterial biofilms on leaf surfaces. The biological control agent, Burkholderia pyroccinia FP62, that rapidly colonizes the leaf surface and forms biofilms, was inoculated onto geranium leaves and incubated in a greenhouse for 7 or 14 days. Cryofixation was not suitable for examination of leaf biofilms because it created a frozen layer over the leaf surface that cracked when exposed to the electron beam and the protective cap required for FIB milling could not be accurately deposited. With chemically fixed samples, it was possible to precisely FIB mill a single cross section (5 µm) or sequential cross sections from a single site without any damage to the surrounding surface. Biofilms, 7 days post-inoculation (DPI), were composed of 2 to 5 bacterial cell layers while biofilms 14 DPI ranged from 5 to greater than 30 cell layers. Empty spaces between bacteria cells in the subsurface structure were observed in biofilms 7- and 14-DPI. Sequential cross sections inferred that the empty spaces were often continuous between FP62 cells and could possibly make up a network of channels throughout the biofilm. FIB SEM was a useful tool to observe the subsurface composition of a foliar biofilm.

Recent nationwide surveys reveal significant decline in students' interest in Math and Sciences. The objective of this project was to inspire young minds in using various techniques involved in Sciences including ScanningElectron Microscopy. We used ScanningElectron Microscope in demonstrating various types of Biological samples. An SEM Tabletop model in the past decade has revolutionized the use of ScanningElectron Microscopes. Using SEM Tabletop model TM 1000 we studied biological specimens of fungal spores, pollen grains, diatoms, plant fibers, dust mites, insect parts and leaf surfaces. We also used fluorescence microscopy to view, to record and analyze various specimens with an Olympus BX40 microscope equipped with FITC and TRITC fluorescent filters, a mercury lamp source, DP-70 digital camera with Image Pro 6.0 software. Micrographs were captured using bright field microscopy, the fluoresceinisothiocyanate (FITC) filter, and the tetramethylrhodamine (TRITC) filter settings at 40X. A high pressure mercury lamp or UV source was used to excite the storage molecules or proteins which exhibited autofluorescence. We used fluorescent microscopy to confirm the localization of sugar beet viruses in plant organs by viewing the vascular bundles in the thin sections of the leaves and other tissues. We worked with the REU summer students on sample preparation and observation on various samples utilizing the SEM. Critical Point Drying (CPD) and metal coating with the sputter coater was followed before observing some cultured specimen and the samples that were soft in textures with high water content. SEM Top allowed investigating the detailed morphological features that can be used for classroom teaching. Undergraduate and graduate researchers studied biological samples of Arthropods, pollen grains and teeth collected from four species of snakes using SEM. This project inspired the research students to pursue their career in higher studies in science and 45% of the

In dystrophic epidermolysis bullosa the genetic defect of anchoring fibrils leads to cleavage beneath the basement membrane, with its consequent loss. We performed scanningelectron microscopy of an inverted blister roof of a case of dystrophic epidermolysis bullosa, confirmed by immunomapping and gene sequencing. With a magnification of 2000 times a net attached to the blister roof could be easily identified. This net was composed of intertwined flat fibers. With higher magnifications, different fiber sizes could be observed, some thin fibers measuring around 80 nm and thicker ones measuring between 200 and 300 nm. PMID:24474107

A new method of comparing light microscopy and scanningelectron microscopy in the study of small cells, such as spermatozoa, that must be examined under oil immersion is described. A grid is etched on the corner of a microscope glass slide, and its inner edges are incised. Its surface area is calculated as a function f the chamber of the critical-point drying apparatus. This method dispenses with the need for any special coverslip and enables the cells to be observed under oil immersion. PMID:6179330

We show that an annular detector placed within the bright field cone in scanning transmission electron microscopy allows direct imaging of light elements in crystals. In contrast to common high angle annular dark field imaging, both light and heavy atom columns are visible simultaneously. In contrast to common bright field imaging, the images are directly and robustly interpretable over a large range of thicknesses. We demonstrate this through systematic simulations and present a simple physical model to obtain some insight into the scattering dynamics.

Annular bright field (ABF) scanning transmission electron microscopy (STEM) is emerging as an important observation mode for its ability to simultaneously image both heavy and light elements. However, recent results have demonstrated that in the limit of a very thin specimen (a few atomic layers), the ABF and high angle annular dark field (HAADF) signals cease to be intuitively related: a phenomenon which is generally irrelevant when imaging 'normal' specimens. ABF/HAADF STEM observations and multislice image simulations of two catalyst samples of differing atomic weights are presented; it is shown that the nature of the ABF signal is specimen dependent.

Previous studies showed that low temperature scanningelectron microscopy (SEM) can be used to record images of precipitated snow crystals, which collectively form structures that are commonly known as snowflakes. Information about the structure of snow crystals can be used to improve models that estimate the water equivalent of the winter snowpack. These models, which are based on satellite microwave data, have practical use in approximating the quantity of water that will be available for crop irrigation and hydroelectric power. Our previous success of using low temperature SEM to image snow crystals has encouraged us to utilize this technique for other types of frozen aqueous specimens.

Bone marrow nuclei fixed with modified Carnoy's, then stained with gallocyanin chromalum followed by air drying showed no difference in morphology when compared by means of scanningelectron microscopy with similar nuclei prepared by critical point drying. Glutaraldehyde at pH 4.0 and 7.1, mercury-containing Zenker's fluid, and chromalum alone, all of which are considered to be nuclear protein cross-linking fixatives, failed to preserve the nuclear morphology as well as gallocyanin-chromalum or critical point prepared bone marro nuclei. PMID:89717

The enamel surfaces of fluorotic teeth were studied by scanningelectron stereomicroscopy. Different whitening treatments were applied to 25 pieces to remove stains caused by fluorosis and their surfaces were characterized by stereomicroscopy in order to obtain functional and amplitude parameters. The topographic features resulting for each treatment were determined through these parameters. The results obtained show that the 3D reconstruction achieved from the SEM stereo pairs is a valuable potential alternative for the surface characterization of this kind of samples. PMID:26930005

In this article, we describe and test a novel way to extend a low temperature scanning tunneling microscope with the capability to measure forces. The tuning fork that we use for this is optimized to have a high quality factor and frequency resolution. Moreover, as this technique is fully compatible with the use of bulk tips, it is possible to combine the force measurements with the use of superconductive or magnetic tips, advantageous for electronic spectroscopy. It also allows us to calibrate both the amplitude and the spring constant of the tuning fork easily, in situ and with high precision.

The aim of this study was to quantify the influence of different mouth rinses on dental plaque. Wearing splints with enamel pieces 24 volunteers rinsed with essential oils, amine/stannous fluoride, or chlorhexidine digluconate (0.12%) mouth rinses. After 24, 48, 72, and 96 h the enamel pieces were analyzed by scanningelectron microscopy. The counts of cocci and bacilli in different plaque layers and the plaque thickness were almost similar using essential oils and amine/stannous fluoride. These results differed significantly from those of chlorhexidine digluconate mouth rinses. The results for plaque thickness were without significant differences between the groups at any appointment. PMID:23758106

Scanningelectron microscopy (SEM) of scales in six species of the fish genus Channa revealed certain features relevant to taxonomic significance. The location of focus, inter-radial distance and width of circuli, inter-circular space, width of radii, shape and size of lepidonts, etc. were found to be different in different species. The importance of SEM of scales in poorly understood taxonomy and phylogeny of the fish genus Channa is discussed with the help of relevant literature. Further, the role of SEM of fish scales for taxonomic applications is discussed in detail. PMID:24870451

The electronic properties of graphitic carbon devices are primarily determined by the contact metal and the carbon band structure. However, inhomogeneities such as substrate imperfections, surface defects, and mobile contaminants also contribute and can lead to transistor-like behaviors. We experimentally investigate this phenomena in the 1-D limit using metallic single-walled carbon nanotubes (SWCNTs) before and after the electrochemical creation of sidewall defects. While scanning gate microscopy readily identifies the defect sites, the energy-dependence of the technique allows quantitative analysis of the defects and discrimination of different defect types. This research is partly supported by the NSF (DMR 08-xxxx).

The three-dimensional findings of the surface and from a cross section from a case of disseminated superficial porokeratois using scanningelectron microscopy are reported. On the surface of the skin, irregular keratin with a serpiginous distribution was seen. A gross aspect of keratin in the hyperkeratotic wall was also observed and compared to the normal area, in which the release of corneocytes seemed normal. The cross-sectional imaging easily identified the cornoid lamella, with compact keratin surrounded by normal stratum corneum. PMID:25387509

The three-dimensional findings of the surface and from a cross section from a case of disseminated superficial porokeratois using scanningelectron microscopy are reported. On the surface of the skin, irregular keratin with a serpiginous distribution was seen. A gross aspect of keratin in the hyperkeratotic wall was also observed and compared to the normal area, in which the release of corneocytes seemed normal. The cross-sectional imaging easily identified the cornoid lamella, with compact keratin surrounded by normal stratum corneum. PMID:25387509

Papanicolaou (Pap)-stained slides are usually observed using a transmitted light microscope for cytopathology. However, progress in pathological examinations has created a need for new diagnostic tools, because cytopathological preparations do not allow additional examinations without a loss of specimen, unlike histopathology. Low-vacuum scanningelectron microscopy (LVSEM) can reveal the surface topography at an ultrastructual resolution without metal coating. The aim of this study was to determine the conditions required for observing Pap-stained slides of oral smears using LVSEM without any loss of specimen and to reexamine the same slides again using light microscopy, while preserving the cytopathological information. PMID:26957591

The morphological structures that permit Oryzophagus oryzae aquatic activities and swimming behavior were studied and compared with various weevils and other relevant species. The use of scanningelectron microscopy facilitated the recognition of three different hydrofuge scales and sensilla. Based on the microscopic observations of behavior, morphological evidence, and comparisons with other curculionid species, it was supported that the gas exchange in O. oryzae adults relies on a subelytral air store maintained by hydrofuge scales and a ribbed margin on the adult elytra. The plastron structure is identical to Lissorhoptrus oryzophilus supporting the application of similar control measures for both species. PMID:22055468

Scanningelectron microscopy was used to characterize the erosion of annealed copper and aluminum surfaces produced by both single- and multiple-particle impacts. Macroscopic 3.2 mm diameter steel balls and microscopic, brittle erodant particles were projected by a gas gun system so as to impact at normal incidence at speeds up to 140 m/sec. During the impacts by the brittle erodant particles, at lower speeds the erosion behavior was similar to that observed for the larger steel balls. At higher velocities, particle fragmentation and the subsequent cutting by the radial wash of debris created a marked change in the erosion mechanism.

Scanning transmission electron microscopy (STEM) of specimens in liquid is possible using a microfluidic chamber with thin silicon nitride windows. This paper includes an analytic equation of the resolution as a function of the sample thickness and the vertical position of an object in the liquid. The equipment for STEM of liquid specimen is briefly described. STEM provides nanometer resolution in micrometer-thick liquid layers with relevance for both biological research and materials science. Using this technique, we investigated tagged proteins in whole eukaryotic cells, and gold nanoparticles in liquid with time-lapse image series. Possibly future applications are discussed.

This is Fiscal Year 1995 Annual Report on the progress of activities relating to the application of scanningelectron microscopy in addressing the Ferrocyanide Safety Issue associated with Hanford Site high-level radioactive waste tanks. The status of the FY 1995 activities directed towards establishing facilities capable of providing SEM based micro-characterization of ferrocyanide tank wastes is described. A summary of key events in the SEM task over FY 1995 and target activities in FY 1996 are presented. A brief overview of the potential applications of computer controlled SEM analytical data in light of analyses of ferrocyanide simulants performed by an independent contractor is also presented

A prototype Phase Aligner (PA) or the ElectronicallyScanned Thinned Array Radiometer instrument has been designed and tested. Implemented in a single Xilinx XC3042PC84-125 Field Programmable Gate Array (FPGA), it is a dual-port register file which allows independent storage and phase coherent retrieval of antenna array data by the Central Processing Unit (CPU). It has dimensions of 4 x 20 bits and can be used at clock frequencies as high as 25 MHz. The ESTAR is a passive synthetic-aperture radiometer designed to sense soil moisture and ocean salinity at L-band.

A prototype Walsh Function Generator (WFG) for the ESTAR (ElectronicallyScanned Thinned Array Radiometer) instrument has been designed and tested. Implemented in a single Xilinx XC3020PC68-50 Field Programmable Gate Array (FPGA), it generates a user-programmable set of 32 consecutive Walsh Functions for noise cancellation in the analog circuitry of the Front-End Modules (FEM's). It is implemented in a 68-pin plastic leaded chip carrier (PLCC) package, is fully testable, and can be used for noise cancellation periods as small as 2 msec.

The present work describes a measuring technique employing the scanningelectron microscope in which values of the true bulk diffusion length are obtained. It is shown that surface recombination effects can be eliminated through application of highly doped surface field layers. The effects of high injection level and low-high junction current generation are investigated. Results obtained with this technique are compared to those obtained by a penetrating radiation (X-ray) method, and a close agreement is found. The SEM technique is limited to cells that contain a back surface field layer.

Processing conditions for manufacturing Ti-6Al-4V components by welding using an electron beam source are known to influence the transformation microstructure in the narrow fusion and heat-affected zones of the weld region. This work examined the effect of multiple-sequence welding on the characteristics of the transformed beta microstructure, using laser scanning confocal microscopy to resolve the Widmanstaetten alpha-beta structure in the fusion zone. The evolution in the alpha interlamellar spacing and plate thickness with processing was then related to microhardness measurements in the weld region.

An outdoor soil burial test was carried out to evaluate the degradation of commercially available LDPE carrier bags in natural soil for up to 2 years. Biodegradability of low density polyethylene films in soil was monitored using both optical and scanningelectron microscopy (SEM). After 7-9 months of soil exposure, microbial colonization was evident on the film surface. Exposed LDPE samples exhibit progressive changes towards degradation after 17-22 months. SEM images reveal signs of degradation such as exfoliation and formation of cracks on film leading to disintegration. The possible degradation mode and consequences on the use and disposal of LDPE films is discussed. PMID:20207547

A prototype Output Data Formatter (ODF) for the ESTAR (ElectronicallyScanned Thinned Array Radiometer) instrument has been designed and tested. It employs programmable logic devices to format and tag correlator data for transmission to Earth. After accepting 170 bits or correlator and error data in parallel, it appends an identification word and then serially passes the data to the Small Explorer Data System (SEDS) for transmission at a maximum rate of greater than 15 Mb/sec. Implemented with two reprogrammable field programmable gate arrays (FPGA's), each contained in a 132-pin plastic pin grid array (PGA) package, the design is cascadeable, fully testable, and low-power.

Summary In this work polyhedron-like gold and sphere-like silver nanoparticles (NPs) were manipulated on an oxidized Si substrate to study the dependence of the static friction and the contact area on the particle geometry. Measurements were performed inside a scanningelectron microscope (SEM) that was equipped with a high-precision XYZ-nanomanipulator. To register the occurring forces a quartz tuning fork (QTF) with a glued sharp probe was used. Contact areas and static friction forces were calculated by using different models and compared with the experimentally measured force. The effect of NP morphology on the nanoscale friction is discussed. PMID:24605279

The proper operation of the ElectronicallyScanned Pressure (ESP) System critical to accomplish the following goals: acquisition of highly accurate pressure data for the development of aerospace and commercial aviation systems and continuous confirmation of data quality to avoid costly, unplanned, repeat wind tunnel or turbine testing. Standard automated setup and checkout routines are necessary to accomplish these goals. Data verification and integrity checks occur at three distinct stages, pretest pressure tubing and system checkouts, daily system validation and in-test confirmation of critical system parameters. This paper will give an overview of the existing hardware, software and methods used to validate data integrity.

In environmental scanningelectron microscopy (ESEM) high pressure applications have become increasingly important. Wet or biological samples can be investigated without time-consuming sample preparation and potential artefacts from this preparation can be neglected. Unfortunately, the signal-to-noise ratio strongly decreases with increasing chamber pressure. To evaluate the high pressure performance of ESEM and to compare different electron microscopes, information about spatial resolution and detector type is not enough. On the one hand, the scattering of the primary electron beam increases, which vanishes the contrast in images; and on the other hand, the secondary electrons (SE) signal amplification decreases. The stagnation gas thickness (effective distance the beam has to travel through the imaging gas) as well as the SE detection system depend on the microscope and for a complete and serious evaluation of an ESEM or low vacuum SEM it is necessary to specify these two parameters. A method is presented to determine the fraction of scattered and unscattered electrons and to calculate the stagnation gas thickness (θ). To evaluate the high pressure performance of the SE detection system, a method is presented that allows for an analysis of a single image and the calculation of the signal-to-noise ratio of this image. All investigations are performed on an FEI ESEM Quanta 600 (field emission gun) and an FEI ESEM Quanta 200 (thermionic gun). These methods and measurements should represent opportunities for evaluating the high pressure performance of an ESEM. PMID:26173072

In this study, we introduce scanningelectron microscopy (SEM) of semithin resin sections. In this technique, semithin sections were adhered on glass slides, stained with both uranyl acetate and lead citrate, and observed with a backscattered electron detector at a low accelerating voltage. As the specimens are stained in the same manner as conventional transmission electron microscopy (TEM), the contrast of SEM images of semithin sections was similar to TEM images of ultrathin sections. Using this technique, wide areas of semithin sections were also observed by SEM, without the obstruction of grids, which was inevitable for traditional TEM. This study also applied semithin section SEM to correlative light and electron microscopy. Correlative immunofluorescence microscopy and immune-SEM were performed in semithin sections of LR white resin-embedded specimens using a FluoroNanogold-labeled secondary antibody. Because LR white resin is hydrophilic and electron stable, this resin is suitable for immunostaining and SEM observation. Using correlative microscopy, the precise localization of the primary antibody was demonstrated by fluorescence microscopy and SEM. This method has great potential for studies examining the precise localization of molecules, including Golgi- and ER-associated proteins, in correlation with LM and SEM. PMID:26206941

Although conventional electron microscopy (EM) requires samples to be in vacuum, most chemical and physical reactions occur in liquid or gas. The Atmospheric ScanningElectron Microscope (ASEM) can observe dynamic phenomena in liquid or gas under atmospheric pressure in real time. An electron-permeable window made of pressure-resistant 100 nm-thick silicon nitride (SiN) film, set into the bottom of the open ASEM sample dish, allows an electron beam to be projected from underneath the sample. A detector positioned below captures backscattered electrons. Using the ASEM, we observed the radiation-induced self-organization process of particles, as well as phenomena accompanying volume change, including evaporation-induced crystallization. Using the electrochemical ASEM dish, we observed tree-like electrochemical depositions on the cathode. In silver nitrate solution, we observed silver depositions near the cathode forming incidental internal voids. The heated ASEM dish allowed observation of patterns of contrast in melting and solidifying solder. Finally, to demonstrate its applicability for monitoring and control of industrial processes, silver paste and solder paste were examined at high throughput. High resolution, imaging speed, flexibility, adaptability, and ease of use facilitate the observation of previously difficult-to-image phenomena, and make the ASEM applicable to various fields. PMID:22088441

An electron bombardment ion thruster was used as an ion source to sputter the surfaces of orthopedic prosthetic metals. Scanningelectron microscopy photomicrographs were made of each ion beam textured surface. The effect of ion texturing an implant surface on its bond to bone cement was investigated. A Co-Cr-W alloy and surgical stainless steel were used as representative hard tissue implant materials to determine effects of ion texturing on bulk mechanical properties. Work was done to determine the effect of substrate temperature on the development of an ion textured surface microstructure. Results indicate that the ultimate strength of the bulk materials is unchanged by ion texturing and that the microstructure will develop more rapidly if the substrate is heated prior to ion texturing.

Scanning tunneling microscopy (STM) methods are used to characterize hydrogen-terminated Si surfaces prepared by a novel method. The surface preparation method is used to expose the Si-SiO2 interface. STM images directly reveal the topographic structure of the Si-SiO2 interface. The dependence of interface topography on oxide preparation conditions observed by STM is compared to the results of conventional surface characterization methods. Also, the electronic structure of the hydrogen-terminated surface is studied by STM spectroscopy. The near-ideal electronic structure of this surface enables direct tunnel spectroscopy measurements of Schottky barrier phenomena. In addition, this method enables probing of semiconductor subsurface properties by STM.

Using mathematical modelling, the authors evaluate the prospects for using beam spot size and scan frequency to control titanium-aluminum alloy composition in electron beam melting and refining. Composition control is evaluated in terms of attainable steady-state extremes of composition, and the time scales required to change hearth and mold composition between those extremes. Mathematical models predict spot size-evaporation and frequency-evaporation relationships by simulating heat transfer in the surface of the melt, and predict overall composition change using simplifying assumptions about the fluid flow field in a melting hearth. Corroborating experiments were run on the electron beam furnace at Sandia National Laboratories in order to verify predicted relationships between frequency and evaporation and to calculate activity coefficients of aluminum and vanadium in titanium.

The development of new nanocrystals with outstanding physicochemical properties requires a full three-dimensional (3D) characterization at the atomic scale. For homogeneous nanocrystals, counting the number of atoms in each atomic column from high angle annular dark field scanning transmission electron microscopy images has been shown to be a successful technique to get access to this 3D information. However, technologically important nanostructures often consist of more than one chemical element. In order to extend atom counting to heterogeneous materials, a new atomic lensing model is presented. This model takes dynamical electron diffraction into account and opens up new possibilities for unraveling the 3D composition at the atomic scale. Here, the method is applied to determine the 3D structure of Au@Ag core-shell nanorods, but it is applicable to a wide range of heterogeneous complex nanostructures. PMID:27367396

Scanningelectron microscopy is frequently applied to dermatological problems, as is evident from a review of the recent literature. In this paper, preparation methods and new techniques allowing experimental studies on the integumentary system are emphasized. Quantitative analysis in the electron microscope by use of energy-dispersive X-ray microanalysis (EDX) has become an important accessory technique. EDX can, for instance, be used to study problems involving physiological changes induced in skin by agents causing contact reactions. Recently, it has been shown that treatment with DNCB, chromate and nickel causes changes in elemental distribution in guinea-pig skin. In addition, elemental uptake in the integumentary system and in pathological inclusions in skin can be analyzed.

Previously we presented (McNally et al., 2012) a model for the ultrastructure of bone showing that the mineral resides principally outside collagen fibrils in the form of 5 nm thick mineral structures hundreds of nanometers long oriented parallel to the fibrils. Here we use high-angle annular dark-field electron tomography in the scanning transmission electron microscope to confirm this model and further elucidate the composite structure. Views of a section cut parallel to the fibril axes show bundles of mineral structures extending parallel to the fibrils and encircling them. The mineral density inside the fibrils is too low to be visualized in these tomographic images. A section cut perpendicular to the fibril axes, shows quasi-circular walls composed of mineral structures, wrapping around apparently empty holes marking the sites of fibrils. These images confirm our original model that the majority of mineral in bone resides outside the collagen fibrils. PMID:23545162

In silicon nitride structural ceramics, the overall mechanical and thermal properties are controlled by the atomic and electronic structures at the interface between the ceramic grains and the amorphous intergranular films (IGFs) formed by various sintering additives. In the last ten years the atomic arrangements of heavy elements (rare-earths) at the Si(3)N(4)/IGF interfaces have been resolved. However, the atomic position of light elements, without which it is not possible to obtain a complete description of the interfaces, has been lacking. This review article details the authors' efforts to identify the atomic arrangement of light elements such as nitrogen and oxygen at the Si(3)N(4)/SiO(2) interface and in bulk Si(3)N(4) using aberration-corrected scanning transmission electron microscopy. PMID:22726263

The development of new nanocrystals with outstanding physicochemical properties requires a full three-dimensional (3D) characterization at the atomic scale. For homogeneous nanocrystals, counting the number of atoms in each atomic column from high angle annular dark field scanning transmission electron microscopy images has been shown to be a successful technique to get access to this 3D information. However, technologically important nanostructures often consist of more than one chemical element. In order to extend atom counting to heterogeneous materials, a new atomic lensing model is presented. This model takes dynamical electron diffraction into account and opens up new possibilities for unraveling the 3D composition at the atomic scale. Here, the method is applied to determine the 3D structure of Au@Ag core-shell nanorods, but it is applicable to a wide range of heterogeneous complex nanostructures.

The primary goal of this project is to evaluate x-ray spectra generated within a scanningelectron microscope (SEM) to determine elemental composition of small samples. This will be accomplished by performing Monte Carlo simulations of the electron and photon interactions in the sample and in the x-ray detector. The elemental inventories will be determined by an inverse process that progressively reduces the difference between the measured and simulated x-ray spectra by iteratively adjusting composition and geometric variables in the computational model. The intended benefit of this work will be to develop a method to perform quantitative analysis on substandard samples (heterogeneous phases, rough surfaces, small sizes, etc.) without involving standard elemental samples or empirical matrix corrections (i.e., true standardless quantitative analysis).

Sections of tissue containing orthopedic materials are currently used to study the compatibility of those materials and to perform electron probe microanalysis at the material-tissue interface. Identification of the cells in contact with the material by Scanningelectron microscopy (SEM) is of interest. We have developed a method for staining cells and tissue structures embedded in polymethyl methacrylate with silver methenamine once the sections have been obtained. Sections were prepared by grinding, and the silver methenamine was applied after oxidation with periodic acid. The procedure was carried out in a microwave oven. Backscatter SEM showed staining of the cell nucleus membrane, chromatin, the nuclear organizers, and the chromosomes of dividing cells. The cytoplasm and the cytoplasmic membrane were also stained. Collagen fibers of the extracellular matrix and the mineralized matrix of bone were labeled. Material particles in the macrophages were easily recognizable and Energy-Dispersive Spectrometer were not impaired by the presence of silver in the preparation. PMID:10190255

The optical behavior of nanostructured materials is of significant interest across many fields. Surface plasmons and their interactions with emitters in nanoscale devices allow us to control light below the coherence limit. By understanding the nature of plasmonics at the local level we can move towards unlocking the full potential of photonic devices. To this end, we examine plasmonic Ag nanoparticles suspended on insulating nanowires by combining cathodoluminescence spectroscopy, electron energy loss spectroscopy, and high resolution annular dark field imaging in a scanning transmission electron microscope. The complementary nature of CL and EELS allow us to extract optical data from a randomly shaped and oriented nanoparticle, and understand its plasmonic behavior in all three spatial dimensions. This work was sponsored by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, as well as NSF-EPS-1004083 and NSF-TN-SCORE.

We report the development of 4D scanning transmission ultrafast electron microscopy (ST-UEM). The method was demonstrated in the imaging of silver nanowires and gold nanoparticles. For the wire, the mechanical motion and shape morphological dynamics were imaged, and from the images we obtained the resonance frequency and the dephasing time of the motion. Moreover, we demonstrate here the simultaneous acquisition of dark-field images and electron energy loss spectra from a single gold nanoparticle, which is not possible with conventional methods. The local probing capabilities of ST-UEM open new avenues for probing dynamic processes, from single isolated to embedded nanostructures, without being affected by the heterogeneous processes of ensemble-averaged dynamics. Such methodology promises to have wide-ranging applications in materials science and in single-particle biological imaging. PMID:21615171

A new method for determining the vitrification rate of pottery depending on the firing temperature was devised using secondary electron images (SEI) of scanningelectron microscope (SEM). Several tests were performed to establish the appropriate operating conditions of SEM and reproducibility as well as to examine the applicability of the method. The grayscale values converted from each pixel of SEI were used to determine the vitrification rate of pottery, which in our study were artificially fired specimens composed of three types of clay. A comparison between the vitrification rate value and appearance temperature of minerals shows that mullite formation starts at 1,100°C, during which the vitrification rate rapidly increases by over 10%. In consequence, the result presented here demonstrates that the new method can be applied to estimate the firing temperature of pottery. PMID:23920198

Mycoplasma is a genus of bacterial pathogen that causes disease in vertebrates. In humans, the species Mycoplasma pneumoniae causes 15% or more of community-acquired pneumonia. Because this bacterium is tiny, corresponding in size to a large virus, diagnosis using optical microscopy is not easy. In current methods, chest X-rays are usually the first action, followed by serology, PCR amplification, and/or culture, but all of these are particularly difficult at an early stage of the disease. Using Mycoplasma mobile as a model species, we directly observed mycoplasma in buffer with the newly developed Atmospheric ScanningElectron Microscope (ASEM). This microscope features an open sample dish with a pressure-resistant thin film window in its base, through which the SEM beam scans samples in solution, from below. Because of its 2-3μm-deep scanning capability, it can observe the whole internal structure of mycoplasma cells stained with metal solutions. Characteristic protein localizations were visualized using immuno-labeling. Cells were observed at low concentrations, because suspended cells concentrate in the observable zone by attaching to sialic acid on the silicon nitride (SiN) film surface within minutes. These results suggest the applicability of the ASEM for the study of mycoplasmas as well as for early-stage mycoplasma infection diagnosis. PMID:22226908

Nematodes of the family Aspidoderidae (Nematoda: Heterakoidea) Skrjabin and Schikobalova, 1947, are widely distributed in the Americas. The family Aspidoderidae includes the subfamilies Aspidoderinae Skrjabin and Schikobalova, 1947, and Lauroiinae Skrjabin and Schikobalova, 1951. These two subfamilies are delineated by the presence or absence of cephalic cordons at the anterior region. The nematodes in the subfamily Aspidoderinae, which includes the genus AspidoderaRailliet and Henry, 1912, are represented by nematodes with anterior cephalic cordons at the anterior end. The nematodes of the genus AspidoderaRailliet and Henry, 1912, are found in the cecum and large intestine of mammals of the orders Edentata, Marsupialia and Rodentia. Species within this genus have many morphological similarities. The use of scanningelectron microscopy allows the specific characterization of the species within this genus. In the present work, we describe a new species of Aspidodera parasite of the large intestine of Didelphis aurita (Mammalia: Didelphidae) Wied-Neuwied, 1826, collected from Cachoeiras de Macacu, Rio de Janeiro. The combination of light and scanningelectron microscopy allowed us a detailed analysis of this nematode. PMID:24129095

Environmental scanningelectron microscopy has been extensively used for studying the wetting properties of different materials. For some types of investigation, however, the traditional ways of conducting in situ dynamic wetting experiments do not offer sufficient control over the wetting process. Here, we present a novel method for controlled wetting of materials in the environmental scanningelectron microscope (ESEM). It offers improved control of the point of interaction between the water and the specimen and renders it more accessible for imaging. It also enables the study of water transport through a material by direct imaging. The method is based on the use of a piezo-driven nanomanipulator to bring a specimen in contact with a water reservoir in the ESEM chamber. The water reservoir is established by local condensation on a Peltier-cooled surface. A fixture was designed to make the experimental setup compatible with the standard Peltier cooling stage of the microscope. The developed technique was successfully applied to individual cellulose fibers, and the absorption and transport of water by individual cellulose fibers were imaged. PMID:23332145

Orifice-to-orifice inconsistencies in data acquired with an electronically-scanned pressure system at the beginning of a wind tunnel experiment forced modifications to the standard, instrument calibration procedures. These modifications included a large increase in the number of calibration points which would allow a critical examination of the calibration curve-fit process, and a subsequent post-test reduction of the pressure data. Evaluation of these data has resulted in an improved functional representation of the pressure-voltage signature for electronically-scanned pressures sensors, which can reduce the errors due to calibration curve fit to under 0.10 percent of reading compared to the manufacturer specified 0.10 percent of full scale. Application of the improved calibration function allows a more rational selection of the calibration set-point pressures. These pressures should be adjusted to achieve a voltage output which matches the physical shape of the pressure-voltage signature of the sensor. This process is conducted in lieu of the more traditional approach where a calibration pressure is specified and the resulting sensor voltage is recorded. The fifteen calibrations acquired over the two-week duration of the wind tunnel test were further used to perform a preliminary, statistical assessment of the variation in the calibration process. The results allowed the estimation of the bias uncertainty for a single instrument calibration; and, they form the precursor for more extensive and more controlled studies in the laboratory.

Membranes and film-on-substrate structures are critical elements for some devices in electronics industry and for Micro Electro Mechanical Systems devices. These structures are normally at the scale of micrometer or even nanometer. Thus, the measurement for the mechanical property of these membranes poses a challenge over the conventional measurements at macro-scales. In this study, a novel bulge test method is presented for the evaluation of mechanical property of micro thin membranes. Three aspects are discussed in the study: (a) A novel bulge test with a ScanningElectron Microscope system realizing the function of loading and measuring simultaneously; (b) a simplified Digital Image Correlation method for a height measurement; and (c) an imaging distortion correction by the introduction of a scanning Moiré method. Combined with the above techniques, biaxial modulus as well as Young's modulus of the polyimide film can be determined. Besides, a standard tensile test is conducted as an auxiliary experiment to validate the feasibility of the proposed method.

Understanding the hierarchical organization of molecules and organelles within the interior of large eukaryotic cells is a challenge of fundamental interest in cell biology. We are using ion-abrasion scanningelectron microscopy (IA-SEM) to visualize this hierarchical organization in an approach that combines focused ion-beam milling with scanningelectron microscopy. Here, we extend our previous studies on imaging yeast cells to image subcellular architecture in human melanoma cells and melanocytes at resolutions as high as approximately 6 and approximately 20 nm in the directions parallel and perpendicular, respectively, to the direction of ion-beam milling. The 3D images demonstrate the striking spatial relationships between specific organelles such as mitochondria and membranes of the endoplasmic reticulum, and the distribution of unique cellular components such as melanosomes. We also show that 10nm-sized gold particles and quantum dot particles with 7 nm-sized cores can be detected in single cross-sectional images. IA-SEM is thus a useful tool for imaging large mammalian cells in their entirety at resolutions in the nanometer range. PMID:19116171

We present results of a combined two-photon photoemission and scanningelectron microscopy investigation to determine the electromagnetic enhancement factors of silver-coated spherical nanoparticles deposited on an atomically flat mica substrate. Femtosecond laser excitation, of the nanoparticles, produces intense photoemission, attributed to near-resonant excitation of localized surface plasmons. Enhancement factors are determined by comparing the respective two-photon photoemission yield measured for equal areas between single nanoparticles to that of the surrounding flat surface. For s-polarized, 400 nm (~ 3.1 eV) femtosecond radiation a distribution of enhancement factors are found with a large percentage (77%) of the nanoparticles falling within a median range. A correlated scanningelectron microscopy analysis demonstrated that the nanoparticles typifying the median of the distribution were characterized by ideal spherical shapes and defect-free morphologies. The single largest enhancement factors were in contrast produced by a very small percentage (8%) of the total, for which evidence of silver defect anomalies were found that contributed to the overall structure of the nanoparticle. Comparisons are made between the experimentally measured enhancement factors and previously reported theoretical predictions of the localized surface plasmon near-field intensities for isolated nanometer-sized silver spheres.

The compound, 2-(2,4-dinitrobenzyl) pyridine, was synthesized in the laboratory; an introductory level electron microscopy study of the macro-crystalline structure was conducted using the scanningelectron microscope (SEM). The structure of these crystals was compared with the macrostructure of the crystal of 2-(2,4-dinitrobenzyl) pyridinium bromide, the hydrobromic salt of the compound which was also synthesized in the laboratory. A scanningelectron microscopy crystal study was combined with a study of the principle of the electron microscope.

Despite many studies of subsurface imaging of carbon nanotube (CNT)-polymer composites via scanningelectron microscopy (SEM), significant controversy exists concerning the imaging depth and contrast mechanisms. We studied CNT-polyimide composites and, by three-dimensional reconstructions of captured stereo-pair images, determined that the maximum SEM imaging depth was typically hundreds of nanometers. The contrast mechanisms were investigated over a broad range of beam accelerating voltages from 0.3 to 30 kV, and ascribed to modulation by embedded CNTs of the effective secondary electron (SE) emission yield at the polymer surface. This modulation of the SE yield is due to non-uniform surface potential distribution resulting from current flows due to leakage and electron beam induced current. The importance of an external electric field on SEM subsurface imaging was also demonstrated. The insights gained from this study can be generally applied to SEM nondestructive subsurface imaging of conducting nanostructures embedded in dielectric matrices such as graphene-polymer composites, silicon-based single electron transistors, high resolution SEM overlay metrology or e-beam lithography, and have significant implications in nanotechnology.

Multimetallic nanoparticles have been attracted greater attention both in materials science and nanotechnology due to its unique electronic, optical, biological, and catalytic properties lead by physiochemical interactions among different atoms and phases. The distinct features of multimetallic nanoparticles enhanced synergetic properties, large surface to volume ratio and quantum size effects ultimately lead to novel and wide range of possibilities for different applications than monometallic counterparts. For instance, PtPd, Pt/Cu, Au-Au3Cu, AgPd/Pt, AuCu/Pt and many other multimetallic nanoparticles have raised interest for their various applications in fuel cells, ethanol and methanol oxidation reactions, hydrogen storage, and so on. The nanostructures were analyzed by transmission electron microscopy (TEM) and by aberration-corrected scanning transmission electron microscopy (Cs-corrected STEM), in combination with high angle annular dark field (HAADF), bright field (BF), energy dispersive X-ray spectroscopy (EDS), and electron energy loss spectroscopy (EELS) detectors. These techniques allowed us to probe the structure at the atomic level of the nanoparticles revealing new structural information and elemental composition of the nanoparticles. The authors would like to acknowledge NSF grants DMR-1103730, ``Alloys at the Nanoscale: The Case of Nanoparticles Second Phase'' and NSF PREM Grant # DMR 0934218.

The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, makingmore » it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Ultimately, simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.« less

A parallel image detection system using an annular pupil for electron optics were developed to realize an increase in the depth of focus, aberration-free imaging and separation of amplitude and phase images under scanning transmission electron microscopy (STEM). Apertures for annular pupils able to suppress high-energy electron scattering were developed using a focused ion beam (FIB) technique. The annular apertures were designed with outer diameter of oe 40 {mu}m and inner diameter of oe32 {mu}m. A taper angle varying from 20 deg. to 1 deg. was applied to the slits of the annular apertures to suppress the influence of high-energy electron scattering. Each azimuth angle image on scintillator was detected by a multi-anode photomultiplier tube assembly through 40 optical fibers bundled in a ring shape. To focus the image appearing on the scintillator on optical fibers, an optical lens relay system attached with CCD camera was developed. The system enables the taking of 40 images simultaneously from different scattered directions.

Change in the cross-sectional profile of a photoresist (PR) pattern due to shrinkage was evaluated to investigate the mechanism of electron beam-induced shrinkage. A scanning transmission electron microscope (STEM) was used to observe the cross-sectional profiles of PR lines after atomic-layer deposition of metal oxide and carbon deposition on the sample surface. A HfO2 thin layer enhanced the profile contrast in the STEM measurements without blurring the edge, which enabled the precise cross-sectional measurement of the PR patterns. We found interesting features associated with shrinkage from the detailed profile change obtained using this method, such as a rounding of the pattern top, a necking of the sidewall profile, a rounding of the foot in the pattern on the organic underlying layer, and voltage-independent sidewall shrinkage under a large electron beam dose. These behaviors along with the results from a Monte Carlo simulation are discussed. Consequently, these observations experimentally clarified that the elastic deformation effect and the impact of the secondary electrons emitted from the spaces around the pattern into the sidewall are important to interpret the change in the shape of the pattern induced by shrinkage.

High-throughput immuno-electron microscopy is required to capture the protein-protein interactions realizing physiological functions. Atmospheric scanningelectron microscopy (ASEM) allows in situ correlative light and electron microscopy of samples in liquid in an open atmospheric environment. Cells are cultured in a few milliliters of medium directly in the ASEM dish, which can be coated and transferred to an incubator as required. Here, cells were imaged by optical or fluorescence microscopy, and at high resolution by gold-labeled immuno-ASEM, sometimes with additional metal staining. Axonal partitioning of neurons was correlated with specific cytoskeletal structures, including microtubules, using primary-culture neurons from wild type Drosophila, and the involvement of ankyrin in the formation of the intra-axonal segmentation boundary was studied using neurons from an ankyrin-deficient mutant. Rubella virus replication producing anti-double-stranded RNA was captured at the host cell's plasma membrane. Fas receptosome formation was associated with clathrin internalization near the surface of primitive endoderm cells. Positively charged Nanogold clearly revealed the cell outlines of primitive endoderm cells, and the cell division of lactic acid bacteria. Based on these experiments, ASEM promises to allow the study of protein interactions in various complexes in a natural environment of aqueous liquid in the near future. PMID:24564988

In the nanoscience era, the properties of many exciting new materials and devices will depend on the details of their composition down to the level of single atoms. Thus the characterization of the structure and electronic properties of matter at the atomic scale is becoming ever more vital for economic and technological as well as for scientific reasons. The combination of atomic-resolution Z-contrast scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) represents a powerful method to link the atomic and electronic structure to macroscopic properties, allowing materials, nanoscale systems, and interfaces to be probed in unprecedented detail. Z-contrast STEM uses electrons that have been scattered to large angles for imaging. The relative intensity of each atomic column is roughly proportional to Z{sup 2}, where Z is the atomic number. Recent developments in correcting the aberrations of the lenses in the electron microscope have pushed the achievable spatial resolution and the sensitivity for imaging and spectroscopy in the STEM into the sub-Angstrom (sub-{angstrom}) regime, providing a new level of insight into the structure/property relations of complex materials. Images acquired with an aberration-corrected instrument show greatly improved contrast. The signal-to-noise ratio is sufficiently high to allow sensitivity even to single atoms in both imaging and spectroscopy. This is a key achievement because the detection and measurement of the response of individual atoms has become a challenging issue to provide new insight into many fields, such as catalysis, ceramic materials, complex oxide interfaces, or grain boundaries. In this article, the state-of-the-art for the characterization of all of these different types of materials by means of aberration-corrected STEM and EELS are reviewed.

In this paper, we demonstrate the utility of single-particle analysis to investigate the chemistry of isolated, individual particles of atmospheric relevance such as NaCl, sea salt, CaCO3, and SiO2. A variety of state-of-th-art scanningelectron microscopy techniques, including environmental scanning electon microscopy and computer-controlled scanningelectron microscopy/energy-dispersive X-ray analysis, were utilized for monitoring and quantifying phase transitions of individual particles, morphology, and compositional changes of individual particles as they react with nitric acid.

Background: The cementodentinal junction (CDJ) forms a biological and structural link between cementum and dentin. This biological link is regarded as a distinct tissue in its own right. Certain important proteins responsible for periodontal regeneration are said to be present in this tissue. Few studies have described the structure and composition of this layer by light and electron microscopy. Scanningelectron microscopic studies pertaining to CDJ in health and disease are few and documentation of periodontal pathological changes of CDJ is unclear. In the first phase of our study, the collagenous architecture of CDJ of healthy teeth has been reported. Aim: The objective of this study is to observe and report periodontal pathological changes in the fibrous or collagenous architecture of CDJ of periodontitis-affected teeth and discuss the probable clinical implications of CDJ in disease. Materials and Methods: Twenty periodontitis-affected teeth were collected and processed for observing under a scanningelectron microscope. Results: The results are as follows: Increased width of interface at CDJ in periodontitis samples (7.1 μ) compared to that of healthy samples; fewer areas of fiber intermingling at CDJ in periodontitis samples as compared to healthy samples; frequent detachment of cementum from dentin during sodium hydroxide maceration of samples. Conclusion: It may be inferred from results that there is a possibility of a definite weakening of CDJ in periodontally affected root surfaces and we believe that clinical procedures such as scaling and root planning may have a detrimental effect on the cementodentinal attachment of periodontally involved root surfaces. PMID:26980960

Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications of semiconductor materials. However, it is still under debate how the defect structure determines the band structure, and therefore, the recombination behavior of electron-hole pairs responsible for the optical and electrical properties of the extended defects. The present paper is a survey of procedures for the spatially resolved investigation of structural and of physical properties of extended defects in semiconductor materials with a scanningelectron microscope (SEM). Representative examples are given for crystalline silicon. The luminescence behavior of extended defects can be investigated by cathodoluminescence (CL) measurements. They are particularly valuable because spectrally and spatially resolved information can be obtained simultaneously. For silicon, with an indirect electronic band structure, CL measurements should be carried out at low temperatures down to 5 K due to the low fraction of radiative recombination processes in comparison to non-radiative transitions at room temperature. For the study of the electrical properties of extended defects, the electron beam induced current (EBIC) technique can be applied. The EBIC image reflects the local distribution of defects due to the increased charge-carrier recombination in their vicinity. The procedure for EBIC investigations is described for measurements at room temperature and at low temperatures. Internal strain fields arising from extended defects can be determined quantitatively by cross-correlation electron backscatter diffraction (ccEBSD). This method is challenging because of the necessary preparation of the sample surface and because of the quality of the diffraction patterns which are recorded during the mapping of the sample. The spatial resolution of the three experimental techniques is compared. PMID:27285177

Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications of semiconductor materials. However, it is still under debate how the defect structure determines the band structure, and therefore, the recombination behavior of electron-hole pairs responsible for the optical and electrical properties of the extended defects. The present paper is a survey of procedures for the spatially resolved investigation of structural and of physical properties of extended defects in semiconductor materials with a scanningelectron microscope (SEM). Representative examples are given for crystalline silicon. The luminescence behavior of extended defects can be investigated by cathodoluminescence (CL) measurements. They are particularly valuable because spectrally and spatially resolved information can be obtained simultaneously. For silicon, with an indirect electronic band structure, CL measurements should be carried out at low temperatures down to 5 K due to the low fraction of radiative recombination processes in comparison to non-radiative transitions at room temperature. For the study of the electrical properties of extended defects, the electron beam induced current (EBIC) technique can be applied. The EBIC image reflects the local distribution of defects due to the increased charge-carrier recombination in their vicinity. The procedure for EBIC investigations is described for measurements at room temperature and at low temperatures. Internal strain fields arising from extended defects can be determined quantitatively by cross-correlation electron backscatter diffraction (ccEBSD). This method is challenging because of the necessary preparation of the sample surface and because of the quality of the diffraction patterns which are recorded during the mapping of the sample. The spatial resolution of the three experimental techniques is compared. PMID:27285177

Nanomaterials including nanoparticles, nanowires and nanotubes play an important role in heterogeneous catalysis. Thanks to the rapid improvement of the electron microscopic techniques and with the advent of aberration corrected electron microscopy as well as theoretical methodologies, the potential effects induced by nanocatalysts are better understood than before by unravelling their atomic structure. A brief introduction to advanced electron microscopic techniques namely aberration corrected scanning transmission electron microscopy (Cs-STEM) is presented and subsequently two examples of nanocatalysts are considered in the present review. The first example will focus on the study of bimetallic/core-shell nanoalloys. In heterogeneous catalysis, catalysts containing two or more metals might show significantly different catalytic properties compared to the parent metals and thus are widely utilized in several catalytic reactions. Atom-by-atom insights of the nanoalloy based catalysts ex: Au-Pd will be described in the present review using a combination of advanced electron microscopic and spectroscopic techniques. A related example on the understanding of bimetallic clusters by HAADF-STEM will also be presented in addition to nanoparticles. In the second case understanding the structure of transition metal chalcogenide based nanocatalysts by HRTEM and aberration corrected STEM, for the case of MoS2 will be discussed. MoS2-based catalysts serve as model catalysts and are employed in the hydrodesulphurisations (HDS) reactions in the removal of sulphur from gasoline and related petrochemical products. They have been studied in various forms including nanowires, nanotubes and nanoplates. Their structure, atomic insights and as a consequence elucidation of their corresponding catalytic activity are thus important.

The chromosomes and interphase cell nuclei of the permanent mouse Sertoli cell line TM4 were examined by chromosome microdissection, FISH, scanningelectron microscopy, and confocal laser scanning microscopy. The already known marker chromosomes m1-m5 were confirmed, and 2 new large marker chromosomes m6 and m7 were characterized. The minute heterochromatic marker chromosomes m4 and m5 were microdissected and their DNA amplified by DOP-PCR. FISH of this DNA probe on TM4 metaphase chromosomes demonstrated that the m4 and m5 marker chromosomes have derived from the centromeric regions of normal telocentric mouse chromosomes. Ectopic pairing of the m4 and m5 marker chromosomes with the centromeric region of any of the other chromosomes (centromeric associations) was apparent in ∼60% of the metaphases. Scanningelectron microscopy revealed DNA-protein bridges connecting the centromeric regions of normal chromosomes and the associated m4 and m5 marker chromosomes. Interphase cell nuclei of TM4 Sertoli cells did not exhibit the characteristic morphology of Sertoli cells in the testes of adult mice as shown by fluorescence microscopy and confocal laser scanning microscopy. PMID:26900862

We demonstrate that vertically aligned carbon nanotubes (CNTs) can be precisely machined in a low pressure water vapor ambient using the electron beam of an environmental scanningelectron microscope. The electron beam locally damages the irradiated regions of the CNT forest and also dissociates the water vapor molecules into reactive species including hydroxyl radicals. These species then locally oxidize the damaged region of the CNTs. The technique offers material removal capabilities ranging from selected CNTs to hundreds of cubic microns. We study how the material removal rate is influenced by the acceleration voltage, beam current, dwell time, operating pressure, and CNT orientation. Milled cuts with depths between 0–100 microns are generated, corresponding to a material removal rate of up to 20.1 μm{sup 3}/min. The technique produces little carbon residue and does not disturb the native morphology of the CNT network. Finally, we demonstrate direct machining of pyramidal surfaces and re-entrant cuts to create freestanding geometries.

A scanningelectron microscope (SEM) with backscatter and secondary electron emission detectors plus a Si(Li) detector for photon yield measurements was used to study bone samples from skull and leg of mice and rats. These animals were either suspended by their tail to induce simulated microgravity, characterized as hind-limb suspension (HLS) or not suspended (control). Analyses of the SEM images and energy dispersive spectrometer (EDS) spectra using Si(Li) detector indicate variation in the lattice structures, and in intensities of the characteristics X-rays, produced from the exposed bone surface due to its interaction with the electron beam. Using Flame software, the X-ray spectra were analyzed and normalized ratios of the elements determined. The elemental analysis indicated a variation in the density of calcium, potassium, and oxygen near the knee joints and near the sutures in the skull bones. The comparison of simulated microgravity subjected samples of the rat skull bones with that of the control samples revealed that in the suture region there was a large increase in the ratio of calcium, and to some degree for phosphorus, suggesting simulated microgravity affects distribution of these elements. Elemental composition for control samples with depth (within the cross section of the leg bones) revealed decrease of oxygen and increase of calcium in the first millimeter of the bone depth after which the relative percentage of elements stayed constant.

We demonstrate that vertically aligned carbon nanotubes (CNTs) can be precisely machined in a low pressure water vapor ambient using the electron beam of an environmental scanningelectron microscope. The electron beam locally damages the irradiated regions of the CNT forest and also dissociates the water vapor molecules into reactive species including hydroxyl radicals. These species then locally oxidize the damaged region of the CNTs. The technique offers material removal capabilities ranging from selected CNTs to hundreds of cubic microns. We study how the material removal rate is influenced by the acceleration voltage, beam current, dwell time, operating pressure, and CNT orientation. Milled cuts with depths between 0-100 microns are generated, corresponding to a material removal rate of up to 20.1 μm3/min. The technique produces little carbon residue and does not disturb the native morphology of the CNT network. Finally, we demonstrate direct machining of pyramidal surfaces and re-entrant cuts to create freestanding geometries.

Observation of growth, synthesis, dynamics and electrochemical reactions in the liquid state is an important yet largely unstudied aspect of nanotechnology. The only techniques that can potentially provide the insights necessary to advance our understanding of these mechanisms is simultaneous atomic-scale imaging and quantitative chemical analysis (through spectroscopy) under environmental conditions in the transmission electron microscope (TEM). In this study we describe the experimental and technical conditions necessary to obtain electron energy loss (EEL) spectra from a nanoparticle in colloidal suspension using aberration corrected scanning transmission electron microscopy (STEM) combined with the environmental liquid stage. At a fluid path length below 400 nm, atomic resolution images can be obtained and simultaneous compositional analysis can be achieved. We show that EEL spectroscopy can be used to quantify the total fluid path length around the nanoparticle, and demonstrate characteristic core-loss signals from the suspended nanoparticles can be resolved and analyzed to provide information on the local interfacial chemistry with the surrounding environment. The combined approach using aberration corrected STEM and EEL spectra with the in situ fluid stage demonstrates a plenary platform for detailed investigations of solution based catalysis and biological research.

This grant furnished funds to purchase a state-of-the-art scanningelectron microscope (SEM) to support our analytical facilities for extraterrestrial samples. After evaluating several instruments, we purchased a JEOL 6500F thermal field emission SEM with the following analytical accessories: EDAX energy-dispersive x-ray analysis system with fully automated control of instrument and sample stage; EDAX LEXS wavelength-dispersive x-ray spectrometer for high sensitivity light-element analysis; EDAX/TSL electron backscatter diffraction (EBSD) system with software for phase identification and crystal orientation mapping; Robinson backscatter electron detector; and an in situ micro-manipulator (Kleindiek). The total price was $550,000 (with $150,000 of the purchase supported by Carnegie institution matching funds). The microscope was delivered in October 2002, and most of the analytical accessories were installed by January 2003. With the exception of the wavelength spectrometer (which has been undergoing design changes) everything is working well and the SEM is in routine use in our laboratory.

Disclosed are lens apparatus in which a beam of charged particlesis brought to a focus by means of a magnetic field, the lens being situated behind the target position. In illustrative embodiments, a lens apparatus is employed in a scanningelectron microscopeas the sole lens for high-resolution focusing of an electron beam, and in particular, an electron beam having an accelerating voltage of from about 10 to about 30,000 V. In one embodiment, the lens apparatus comprises an electrically-conducting coil arranged around the axis of the beam and a magnetic pole piece extending along the axis of the beam at least within the space surrounded by the coil. In other embodiments, the lens apparatus comprises a magnetic dipole or virtual magnetic monopole fabricated from a variety of materials, including permanent magnets, superconducting coils, and magnetizable spheres and needles contained within an energy-conducting coil. Multiple-array lens apparatus are also disclosed for simultaneous and/or consecutive imaging of multiple images on single or multiple specimens. The invention further provides apparatus, methods, and devices useful in focusing charged particle beams for lithographic processes.

Magnetic singularities associated with magnetic vortex cores are a common feature in patterned magnetic nanostructures. Their small size, on the order of 10 nm, makes them technologically interesting, but also difficult to measure or image directly. We used ScanningElectron Microscopy with Polarization Analysis (SEMPA) to image magnetic vortices in a wide variety of patterned nanostructures. Since SEMPA can measure both the in-plane and the out-of-plane component of the surface magnetization, SEMPA can potentially determine both the chirality and the polarity of the vortex core, simultaneously. Samples consisted of NiFe (25nm) / Ta (3nm), and other soft magnetic films, patterned by electron beam lithography and lift-off into disks with various diameters. The films were grown on 85nm thick SiN membranes to reduce image degradation from backscattered electrons. The experimental results were compared to micromagnetic simulations and the vortex core profile showed a good correspondence with theoretical predictions, which considers only the exchange and magnetostatic energy. This work has been supported in part by the NIST-CNST/UMD-NanoCenter Cooperative Agreement.

A new scanningelectron microscopic method was developed for gaining both phylogenetic and morphological information about target microbes using in situ hybridization with rRNA-targeted oligonucleotide probes (SEM-ISH). Target cells were hybridized with oligonucleotide probes after gold labeling. Gold enhancement was used for amplification of probe signals from hybridized cells. The hybridized cells released a strong backscatter electron signal due to accumulation of gold atoms inside cells. SEM-ISH was applied to analyze bacterial community composition in freshwater samples, and bacterial cell counts determined by SEM-ISH with rRNA-targeted probes for major phyla within the domain Bacteria were highly correlated to those by fluorescent in situ hybridization (FISH). The bacterial composition on surface of river sediment particles before and after cell dispersion treatment by sonication was successfully revealed by SEM-ISH. Direct enumeration of bacterial cells on the surface of sonicated sediment particles by SEM-ISH demonstrated that members of Cytophaga-Flavobacterium existed tightly on the surface of particles. SEM-ISH allows defining the number and distribution of phylogenetically defined cells adherent to material surfaces, which is difficult in FISH, and it gives new insight into electron microscopic studies of microorganisms in their natural environment. PMID:16151145

It is clear that complete understanding of macroscopic properties of materials is impossible without a thorough knowledge of behavior at the smallest length scales. While the past 25 years have witnessed major advances in a variety of techniques that probe the nanoscale properties of matter, electrical transport measurements -- the heart of condensed matter research -- have lagged behind, never progressing beyond bulk measurements. This thesis describes a scanning tunneling potentiometry (STP) system developed to simultaneously map the transport-related electrochemical potential distribution of a biased sample along with its surface topography, extending electronic transport measurements to the nanoscale. Combining a novel sample biasing technique with a continuous current-nulling feedback scheme pushes the noise performance of the measurement to its fundamental limit - the Johnson noise of the STM tunnel junction. The resulting 130 nV voltage sensitivity allows us to spatially resolve local potentials at scales down to 2 nm, while maintaining atomic scale STM imaging, all at scan sizes of up to 15 microns. A mm-range two-dimensional coarse positioning stage and the ability to operate from liquid helium to room temperature with a fast turn-around time greatly expand the versatility of the instrument. Use of carefully selected model materials, combined with excellent topographic and voltage resolution has allowed us to distinguish measurement artifacts caused by surface roughness from true potentiometric features, a major problem in previous STP measurements. The measurements demonstrate that STP can produce physically meaningful results for homogeneous transport as well as non-uniform conduction dominated by material microstructures. Measurements of several physically interesting materials systems are presented as well, revealing new behaviors at the smallest length sales. The results establish scanning tunneling potentiometry as a useful tool for physics and

Lophelia pertusa is a cold-water coral, which may form reefs by the association of multiple coralites within which a polyp lives. Each individual polyp builds an aragonite skeleton by an initial phase of early mineralization (traditionally referred to as centres of calcification) from which aragonite fibres grow in thickening deposits. The skeleton wall features successive optically opaque and translucent bands previously attributed to different regimes of growth as either uniform in crystal orientation (translucent bands) or with a chaotic organization (opaque bands). The processes involved in any organizational changes are still unknown. Microlayers in the coral wall, which represent separate periods of skeletal growth, have been recently identified and described. These growth patterns are readily visible under scanningelectron microscope (SEM) after etching in dilute formic acid, but they do not necessarily form continuously visible structures. Here we present high quality SEM images and electron backscatter diffraction (EBSD) maps to study aragonite fibre orientation across the wall of L. pertusa. Both microlayers and opaque and translucent bands are compared to the crystallographic orientation of the aragonite fibres. EBSD maps and SEM images indicate that aragonite fibres do not exhibit a chaotic orientation, even in opaque bands. The absence of continuity of microlayers is partially explained by an association of multiple crystallographic preferred orientations of aragonite fibres. In the case of L. pertusa, careful textural characterisation is necessary prior to elemental or isotope analysis in order to select a skeletal transect representing a linear and continuous time period.

Single electron transistors (SETs) are known to be extremely sensitive electrometers owing to their high charge sensitivity. In this work, we report the design, fabrication, and characterization of a silicon-on-insulator-based SET scanning probe. The fabricated SET is located about 10 μm away from the probe tip. The SET with a quantum dot of about 70 nm in diameter exhibits an obvious Coulomb blockade effect measured at 4.1 K. The Coulomb blockade energy is about 18 meV, and the charge sensitivity is in the order of 10‑5‑10‑3 e/Hz1/2. This SET scanning probe can be used to map charge distribution and sense dynamic charge fluctuation in nanodevices or circuits under test, realizing high sensitivity and high spatial resolution charge detection. Project supported by the Instrument Developing Project of the Chinese Academy of Sciences (No. YZ201152), the National Natural Science Foundation of China (No. 11403084), the Fundamental Research Funds for Central Universities (Nos. JUSRP51510, JUDCF12032), and the Graduate Student Innovation Program for Universities of Jiangsu Province (No. CXLX12_0724).

Tricalciumsilicate (C(3)S, Alite) is the major component of the Portland cement clinker, The hydration of the Alite is decisive for the properties of the resulting material due to the high content in cement. The mechanism of the hydration of C(3)S is very complicated and not yet fully understood. There are some models that describe the hydration of C(3)S in various ways. The Environmental ScanningElectron Microscopy (ESEM) working in gaseous atmosphere enables high-resolution dynamic observations of structure of materials, from micrometre to nanometre scale. This provides a new perspective in material research. ESEM significantly allows imaging of specimen in their natural state without the need for special preparation (coating, drying, etc.) that can alter the physical properties. This paper presents the results of our experimental studies of hydration of C(3)S using ESEM. The ESEM turned out to be an important extension of the conventional scanning microscopy. The purpose of these investigations is to gain insight of hydration mechanism to determine which hydration products are formed and to analyze if there are any differences in the composition of the hydration products. PMID:25882158

Micrographs of PICA (Phenolic Impregnated Carbon Ablator) taken using a ScanningElectron Microscope (SEM) and 3D images taken with a Computed Tomography (CT) system are examined. PICA is a carbon fiber based composite (Fiberform ) with a phenolic polymer matrix. The micrographs are taken at different surface depths and at different magnifications in a sample after arc jet testing and show different levels of oxidative removal of the charred matrix (Figs 1 though 13). CT scans, courtesy of Xradia, Inc. of Concord CA, were captured for samples of virgin PICA, charred PICA and raw Fiberform (Fig. 14). We use these images to calculate the thermal conductivity (TC) of these materials using correlation function (CF) methods. CF methods give a mathematical description of how one material is embedded in another and is thus ideally suited for modeling composites like PICA. We will evaluate how the TC of the materials changes as a function of surface depth. This work is in collaboration with ETH-Zurich, which has expertise in high temperature materials and TC modeling (including CF methods).

This work deals with the analysis of the electronic subsystem of a multiwavelength elastic scanning lidar. Several calibration tests are applied to the Cubatão scanning lidar placed at the industrial area of Cubatão in the State of São Paulo (Brazil), in order to improve the knowledge of its performing itself and to design protocols for correcting lidar signal for undesirable instrumental effects. In particular, the trigger delay is assessed by means of zero-bin and bin-shift tests for analog (AN) and photo-counting (PC) signals, respectively. Dark current test is also performed to detect potential range-dependency that could affect lidar products. All tests were performed at different spatial resolutions. These instrumental corrections were applied to a case study of data acquired for characterizing the optical and microphysical properties of particles in an industrial flare. To that aim, a graphical method based on the space defined by the extinction-related Angström exponent versus its spectral curvature is used to derive the contribution of fine aerosol to extinction and the size of the fine aerosols in the industrial flare, therefore revealing features of the processes occurring inside the flame. Our study demonstrates the potential of this new technique for the study and measurement of industrial emissions. PMID:25607056

The trend towards minimization in ultralarge-scale integration (ULSI) fabrication requires an increasingly precise motion accuracy for an XY-stage in a high-vacuum environment of electron beam (e-beam) systems. Aerostatic bearings allow for an extremely smooth motion, because the slider of the XY-stage is supported by an air film under a noncontact condition. However, such an XY-stage in aerostatic bearings is not easily introduced into the e-beam systems because of the markedly high amount of exhaust gas leaking into a vacuum chamber. In this paper, we describe a newly developed hybrid XY-stage guided by aerostatic bearings equipped with a noncontact seal mechanism for scanning motion and by mechanical rolling guides for stepping motion.

Amorphous materials are metastable, more reactive than the crystalline ones, and have to be evaluated before pharmaceutical compound formulation. Amorphicity is interpreted as a spatial chaos, and patterns of molecular aggregates of dexamethasone, D, were investigated in this paper by using fractal dimension, FD. Images having three magnifications of D were taken from an optical microscope, OM, and with eight magnifications, from a scanningelectron microscope, SEM, were analyzed. The average FD for pattern irregularities of OM images was 1.538, and about 1.692 for SEM images. The FDs of the two kinds of images are less sensitive of threshold level. 3D images were shown to illustrate dependence of FD of threshold and magnification level. As a result, optical image of single scale is enough to characterize the drug amorphicity. As a result, the OM image at a single scale is enough to characterize the amorphicity of D.

Electronicallyscanned pressure (ESP) modules have been developed that can operate in ambient and in cryogenic environments, particularly Langley's National Transonic Facility (NTF). Because they can operate directly in a cryogenic environment, their use eliminates many of the operational problems associated with using conventional modules at low temperatures. To ensure the accuracy of these new instruments, calibration was conducted in a laboratory simulating the environmental conditions of NTF. This paper discusses the calibration process by means of the simulation laboratory, the system inputs and outputs and the analysis of the calibration data. Calibration results of module M4, a wide temperature ESP module with 16 ports and a pressure range of +/- 4 psid are given.

Vermicompost was produced from flower waste inoculated with biofertilizers using the earthworm Eisenia fetida. Principal component analysis (PCA) and cluster analysis (CA) were carried out on the basis of physicochemical parameters of vermicomposted samples. From the results of the PCA and CA, it was possible to classify two different groups of vermicompost samples in the following categories: E2 and E5; and E1, E3, E4, and control. Scanningelectron microscopy and biodynamic circular paper chromatography analysis were used to investigate the changes in surface morphology and functional groups in the control and vermicompost products. SEM analysis of E1-E5 shows more fragment and pores than the control. Chromatographic analysis of vermicompost indicated the mature condition of the compost materials. PMID:24634991

Tetratrichomonas didelphidis is a flagellate protozoan found in the intestine of opossums Didelphis marsupialis, Didelphis albiventris, and Lutreolina crassicaudata. The isolate used in this study was from L. crassicaudata and it was cultivated in monoxenic culture with Escherichia coli in Diamond (TYM) medium without maltose and with starch solution (trypticase-yeast extract-starch), pH 7.5 at 28 degrees C. Scanningelectron microscopy showed the fine morphological features of the trophozoites: the emergence of the anterior flagella, the structure of the undulating membrane, the axostyle and posterior flagellum. In addition, we described spherical forms that are probably pseudocysts. Our data will contribute to a better understanding of surface structures in T. didelphidis. PMID:17252276

Digital image correlation (DIC) is a powerful, length-scale-independent methodology for examining full-field surface deformations. Recently, it has become possible to combine DIC with scanningelectron microscopy (SEM), enabling the investigation of small-scale deformation mechanisms such as the strains accommodated within grains in polycrystalline metals, or around micro-scale constituents in composite materials. However, there exist significant challenges that need to be surmounted before the combination of DIC and SEM (here termed SEM-DIC) can be fully exploited. One of the primary challenges is the ability to pattern specimens at microstructural length scales with a random, isotropic and high contrast pattern needed for DIC. This paper provides a thorough survey of small-scale patterning methods for SEM-DIC and discusses their advantages and disadvantages for different applications.

The surface of rabbit, cat, monkey and human semilunar cartilages was examined with the scanningelectron microscope. A common feature was the occurrence of numerous ridges, undulations and furrows on the surface, but this was thought to be due to marked shrinkage and distortion of cartilage not firmly attached to bone. Humps were seen on the semilunar cartilages of young animals, but pits occurred in adults. This is thought to reflect a maturation change. Humps were seen in a young human semilunar cartilage, but pits were not seen in adult specimens. It is not clear whether pits are truly absent or just masked by the severe ridging produced during the preparation of large human specimens. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 Fig. 16 PMID:99411

The development of electron, and scanning probe microscopies in the second half of the twentieth century have produced spectacular images of internal structure and composition of matter with, at nanometer, molecular, and atomic resolution. Largely, this progress was enabled by computer-assisted methods of microscope operation, data acquisition and analysis. The progress in imaging technologies in the beginning of the twenty first century has opened the proverbial floodgates of high-veracity information on structure and functionality. High resolution imaging now allows information on atomic positions with picometer precision, allowing for quantitative measurements of individual bond length and angles. Functional imaging often leads to multidimensional data sets containing partial or full information on properties of interest, acquired as a function of multiple parameters (time, temperature, or other external stimuli). Here, we review several recent applications of the big and deep data analysis methods to visualize, compress, and translate this data into physically and chemically relevant information from imaging data.

Initial results from an ultrahigh-vacuum (UHV) third-order spherical aberration (Cs) corrector for a dedicated scanning transmission electron microscopy, installed at the National Institute for Materials Science, Tsukuba, Japan, are presented here. The Cs corrector is of the dual hexapole type. It is UHV compatible and was installed on a UHV column. The Ronchigram obtained showed an extension of the sweet spot area, indicating a successful correction of the third-order spherical aberration Cs. The power spectrum of an image demonstrated that the resolution achieved was 0.1 nm. A first trial of the direct measurement of the fifth-order spherical aberration C5 was also attempted on the basis of a Ronchigram fringe measurement. PMID:19830936

During prior studies it could be demonstrated that engaging a frequency double Alexandrite-laser allows a fast and strictly selective ablation of supra- and subgingival calculus. Furthermore, the removal of unstained microbial plaque was observed. First conclusions were drawn following light microscopic investigations on undecalcified sections of irradiated teeth. In the present study the cementum surface after irradiation with a frequency doubled Alexandrite-laser was observed by means of a scanningelectron microscope. After irradiation sections of teeth were dried in alcohol and sputtered with gold. In comparison irradiated cementum surfaces of unerupted operatively removed wisdom teeth and tooth surfaces after the selective removal of calculus were investigated. A complete removal of calculus was observed as well as a remaining smooth surface of irradiated cementum.

This study reports the observation of six different zincblende compound semiconductors in [110] projection using large-collection-angle bright-field (LABF) imaging with an aberration-corrected scanning transmission electron microscope. Phase contrast is completely suppressed when the collection semi-angle is set equal to the convergence semi-angle and there are no reversals in image contrast with changes in defocus or thickness. The optimum focus for imaging closely separated pairs of atomic columns (‘dumbbells’) is unique and easily recognized, and the positions of atomic columns occupied by heavier atoms always have darker intensity than those occupied by lighter atoms. Thus, the crystal polarity of compound semiconductors can be determined unambiguously. Moreover, it is concluded that the LABF imaging mode will be highly beneficial for studying other more complicated heterostructures at the atomic scale.

Background: To determine the susceptibility of teeth for repigmentation after bleaching. Materials and Methods: Forty premolars were assigned to three groups (n = 12). Group 1 was bleached using 30% w/v hydrogen peroxide 15 min 3 times a day every other day for 4 days. In Group 2 was bleached using 16% carbamide peroxide (Polanight), 90 min a day for 15 days. 2 days later, the shades of the bleached teeth were recorded. Remaining 4 teeth were bleached according to Group 1 and 2 and were subjected to atomic force microscopy, scanningelectron microscopy analysis. Results: Specimens of athome bleaching were lighter than the specimens of inoffice bleaching. Conclusion: The susceptibility of enamel to pigmentation can be increased after bleaching, and pigmentation is greater if bleaching is performed with H2O2. The percentage change (lighter) was more for athome bleaching specimens as compared to inoffice bleaching specimens. PMID:25395800

The aim of this study was to describe the dentine morphology of sloths (Bradypus tridactylus). The sloth teeth were removed and prepared for light microscopy (LM) and scanningelectron microscopy analyses (SEM). LM revealed two patterns of tubular dentins: an outer with dentinary tubules over the all tooth length and one in the inner part with larger diameter and more spaced tubules, when compared to those present in the outer dentine. These findings were confirmed by SEM, which revealed a tubular pattern in the outer dentine like in humans. The inner dentine displayed pared grouped tubules that were characterized as vascular channels. It can be concluded that this sloth species present two types of dentins: an inner dentin (ortodentin) and an outer dentin characterized as a vascular dentin. This suggests a partial evolutive/adaptive process of this dental tissue, as compared to other mammalian species. PMID:23410180

In this work, palm oil biomass consisting of empty fruit bunch (EFB), mesocarp fibre and palm kernel shell (PKS) were chosen as raw material for torrefaction process. Torrefaction process was conducted at various temperatures of 240 °C, 270 °C and 300 °C with a residence time of 60 minutes. The morphology of the raw and torrefied biomass was then observed through ScanningElectron Microscopy (SEM) images. Also, through this experiment the correlation between the torrefaction temperatures with the volatile gases released were studied. From the observation, the morphology structure of the biomass exhibited inter-particle gaps due to the release of volatile gases and it is obviously seen more at higher temperatures. Moreover, the change of the biomass structure is influenced by the alteration of the lignocellulose biomass.

A new wavelength - dispersive X-ray spectrometer for scanningelectron microscopy (SEM) has been developed. This spectrometer can cover an energy range from 50 eV to 1120 eV by using an array made of seventeen reflection zone plates. Soft X-ray emission spectra of simple elements of Li, Be, B, C, N, Ti, V, O, Cr, Mn, Fe, Co, Ni, Cu, Zn and Ga were measured. The overall energy resolving power on the order of E/ΔE ~80 to 160 has been demonstrated. Spectrometer with 200 reflection zone plates has been used as a multi-channel analyser in the energy range of 100 - 1000 eV for quasi - continuous spectra measurements. The predicted energy-resolving power on the order of E/ΔE = 50 has been achieved in the entire energy range. PMID:25090506

We have previously shown that parasite eggs have been identified in the coprolites of Korean mummies. These eggs have shed light on parasitic infection patterns in Korean populations living several hundred years ago. We conducted a scanningelectron microscopy (SEM) study on ancient Trichuris trichiura, Ascaris lumbricoides, Metagonimus yokogawai, Paragonimus westermani, and Gymnophalloides seoi eggs recovered from Korean mummies of the Joseon Dynasty. We anticipated that the taphonomic conditions of mummification would alter the eggs of certain species but not of others. Our SEM data show that each species of ancient egg exhibited different degrees of preservation. Thus, some of them, for example, M. yokogawai, exhibited a better preservation status than others, suggesting that they should be the first candidates considered when choosing subjects for future paleoparasitological studies. PMID:18601576

Scattering scanning near-field optical microscopy (s-SNOM) has been demonstrated as a valuable tool for mapping the optical and optoelectronic properties of materials with nanoscale resolution. Here we report experimental evidence that trapped electric charges injected by an electron beam at the surface of dielectric samples affect the sample-dipole interaction, which has direct impact on the s-SNOM image content. Nanoscale mapping of the surface trapped charge holds significant potential for the precise tailoring of the electrostatic properties of dielectric and semiconductive samples, such as hydroxyapatite, which has particular importance with respect to biomedical applications. The methodology developed here is highly relevant to semiconductor device fabrication as well. PMID:26974112

The deposition of insoluble salts onto surfaces in process systems represents an important operational problem. Mineral scale formation (e.g. CaCO 3 and BaSO 4) can result from fluid streams becoming supersaturated when incompatible waters combine (e.g. in oil recovery) or can be formed when cathodic protection is applied and electrodeposition occurs. In this study, electrodeposition is studied on metal rotating disk electrodes (RDE) in artificial seawater under static conditions and under rotation at 400 rpm. Also, a Ca-free brine and a Mg-free brine of the same dissolved solids level were used in static tests. The focus of the study is the assessment of the electrochemical response of the system under potentiostatic control and correlation of the current versus time measurements to the characteristics of the scale determined via scanningelectron microscopy and atomic force microscopy analysis.

After etching for one minute with 35 per cent phosphoric acid, thirty-eight permanent teeth were furnished with plastic brackets. An additional twelve teeth were used as references and were etched but were not furnished with brackets. Four teeth served as untreated controls. Eight brackets had fallen off one week later. The remaining brackets were removed with various instruments. All the teeth were extracted and examined by scanningelectron microscopy (SEM). On all of the teeth originally furnished with brackets, residual acrylic was found on the tooth surface. The SEM examination was supplemented with energy-dispersive x-ray analysis (ED) which confirmed that the observed residues differed in their chemical composition from the dental substance. PMID:326059

A conceptual design for the Two-Dimensional, Electronically Steered Thinned Array Radiometer (ESTAR) is described. This instrument is a synthetic aperture microwave radiometer that operates in the L-band frequency range for the measurement of soil moisture and ocean salinity. Two auxiliary instruments, an 8-12 micron, scanning infrared radiometer and a 0.4-1.0 micron, charge coupled device (CCD) video camera, are included to provided data for sea surface temperature measurements and spatial registration of targets respectively. The science requirements were defined by Goddard Space Flight Center. Instrument and the spacecraft configurations are described for missions using the Pegasus and Taurus launch vehicles. The analyses and design trades described include: estimations of size, mass and power, instrument viewing coverage, mechanical design trades, structural and thermal analyses, data and communications performance assessments, and cost estimation.

The main purpose of this study is to extend the microscopic investigations of the pecten oculi in the quail in order to add some information on the unresolved functional anatomy of this unique avian organ. The pecten oculi of the quail was studied by scanningelectron microscopy. Eighteen- to-twenty two highly vascularised accordion-like folds were joined apically by a heavily pigmented bridge of tissue, which holds the pecten in a fanlike shape, widest at the base. The structure of the double layered limiting membrane was recorded. The presence of hyalocytes with macrophage-like appearance was illustrated. It is assumed that the pecten oculi of the quail resembles that of the chicken. Illustrated morphological features of this species may add information on the active physiological role of the pecten. But still, the functional significance of this organ is a matter of controversies. PMID:24198967

Different non-ionic cellulose ethers like methyl cellulose (MC), hydroxypropyl cellulose (HPC) and hydroxypropylmethyl cellulose (HPMC) were investigated. The characterization of the cellulose ethers was carried out by thermogravimetry and sorption/desorption isotherms. Differences in the properties of the cellulose ether films were described by time-dependent contact angle measurements. Changes in molecular structure of the raw materials, gels and films caused by water contact were studied using Raman spectroscopy. Differences between the substitution types and changes due to the gel or film formation were observed. An environmental scanningelectron microscopy (ESEM) technique was used to distinguish the morphological behaviour of the cellulose ether films in contact with water. Based on in-situ ESEM experiments, the swelling and drying behaviour of the various stages of cellulose ether films (film-hydrated film-dried film) were quantified by using image analysis. PMID:15969923

An easy and low-cost method to elaborate a container to dehydrate nematodes and other meiofauna in order to process them for scanningelectron microscopy (SEM) is presented. Illustrations of its elaboration, step by step, are included. In addition, a brief methodology to process meiofauna, especially nematodes and kinorhynchs, and illustrations are provided. With this methodology it is possible to easily introduce the specimens, to lock them in a closed chamber allowing the infiltration of fluids and gases (ethanol, acetone, carbon dioxide) but avoiding losing the specimens. After using this meiofauna basket for SEM the results are efficient. Examples of nematode and kinorhynch SEM pictures obtained using this methodology are also included. PMID:26178782

The vasculature of lumbar posterior root ganglia was investigated in human fetuses aged 17-24 weeks; using the corrosion casting technique and scanningelectron microscopy. The arterial supply consisted of one main artery and occasional arterioles entering the ganglion at its pole and running axially, while the venous drainage was located at the periphery of the ganglion, thus indicating a centrifugal pattern of blood flow. The dense capillary network of the ganglion showed the roughly parallel course of the vessels in the central zone and an irregular arrangement in the peripheral zone where capillaries formed "nests", probably surrounding individual perikaryons of ganglionic cells. The capillaries had a sinusoidal character with numerous dilatations about twice the normal capillary size, as well as occasional larger vascular spaces resulting from capillary interconnections and suggesting the intussusceptive type of angiogenesis. PMID:9488902

Under examination by scanningelectron microscopy were film samples of the subcutaneous connective tissue. The surface of the films from intact mice was even and smooth, fibroblasts have a spread pattern. Following the saline injection the film was even, collagen fibres, differing in the character of surface and the size of diameter, were readily seen. The collagen fibres formed a multilayer system with a definite orientation inside the layer. After DMBA injection the film surface would get uneven and tuberous, the fibroblast body rising over the film surface, thus the orientation of fibres and all strata was disturbed. There was a spacial rearrangement of all tissue components. It is suggested that carcinogenic agents affecting the relationship between tissue components could interfere the contact inhibition of cell division and result in the development of focal cell proliferates. PMID:113934

We provide data obtained by scanningelectron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) on the interaction of ingested tungsten nanofibers with epithelial cells of the digestive tubes of a test organism Porcellio scaber. Conventional toxicity endpoints including feeding behaviour, weight loss and mortality were also measured in each investigated animal. No toxicity was detected in any of exposed animals after 14 days of feeding on tungsten nanofiber dosed food, but when nanofibers enter the digestive system they can react with epithelial cells of the digestive tubes, becoming physically inserted into the cells. In this way, nanofibers can injure the epithelial cells of digestive gland tubes when they are ingested with food. Our SEM data suggest that peristaltic forces may have an important role, not predicted by in vitro experiments, in the interactions of nanomaterials with digestive intestinal cells. PMID:23742956

The application of annular bright field (ABF) and medium-angle annular dark field (MAADF) scanning transmission electron microscopy (STEM) imaging to crystalline defect analysis has been extended to dislocations and stacking faults (SFs). Dislocations and SFs have been imaged under zone-axis and two-beam diffraction conditions. Comparing to conventional two-beam diffraction contrast images, the ABF and MAADF images of dislocations and SFs not only are complementary and symmetrical with their peaks at dislocation core and SFs plane, but also show similar extinction phenomenon. It is demonstrated that conventional TEM rules for diffraction contrast, i.e. g · b and g · R invisibility criteria remain applicable. The contrast mechanism and extinction of dislocation and SFs in ABF and MAADF STEM are illuminated by zero-order Laue zone Kikuchi diffraction.

Surface pathology of inner ear structures so far described in detail concern cochlear and vestibular hair cells and the stria vascularis. In man, surgical intervention into the inner ear is very uncommon and when performed is in general with the primary objective of destroying the diseased peripheral end organs. The vast majority of inner ear tissue available for use with scanningelectron microscopy (SEM) is therefore obtained from animals. The present paper reviews the progression of surface pathology caused by aminoglycoside antibiotics, acoustic overstimulation and in a guinea pig strain with genetic inner ear disease. The primary site of onset of surface pathology differs, depending on the underlying cause. Advanced surface pathology shows a similar type of morphological degeneration independent of cause. The combination of SEM and energy dispersive X-ray microanalysis (XRMA) of inner ear pathology has as yet been reported in only three studies, all concerning inner ear fluids or otoconia.

We have applied the scanningelectron microscope (SEM) to obtain autoradiographs of particles of /sup 239/PuO/sub 2/ deposited in rat lung. The technique was used to obtain quantitative information on the clearance rates of particles from the alveoli, bronchioles and trachea up to 240 d after exposure. At all times, the concentration of particles on the surface of the bronchioles was an order of magnitude greater than on the tracheal surface. The clearance of Pu from both regions followed a biphasic pattern, similar to that obtained by radiometric analysis of the whole lung. Most of the radiation dose to the bronchiolar epithelium originated from Pu particles in peribronchiolar alveoli in which they were preferentially retained, compared to other alveolar regions. The prolonged retention of particles in the peribronchiolar alveoli may be a significant factor in the induction of lung carcinomas.

Nematode worms account for the vast majority of the animals in the biosphere. They are colossally important to global public health as parasites, and to agriculture both as pests and as beneficial inhabitants of healthy soil. Amphid neurons are the anterior chemosensory neurons in nematodes, mediating critical behaviors including chemotaxis and mating. We are examining the cellular morphology and external anatomy of amphid neurons, using fluorescence microscopy and scanningelectron microscopy, respectively, of a wide range of soil nematodes isolated in the wild. We use both classical systematics (e.g. diagnostic keys) and molecular markers (e.g. ribosomal RNA) to classify these wild isolates. Our ultimate aim is to build a detailed anatomical database in order to dissect genetic pathways of neuronal development and function across phylogeny and ecology. Research supported by NSF grants 092304, 0806660, 1058829 and Lock Haven University FPDC grants

Copper and gold films (0.2 to 2 microns) were ion plated onto polished 304-stainless-steel surfaces. These coatings were examined by scanningelectron microscopy for coating growth defects. Three types of defects were distinguished: nodular growth, abnormal or runaway growth, and spits. The cause and origin for each type of defect was traced. Nodular growth is primarily due to inherent substrate microdefects, abnormal or runaway growth is due to external surface inclusions, and spits are due to nonuniform evaporation. All these defects have adverse effects on the coatings. They induce stresses and produce porosity in the coatings and thus weaken their mechanical properties. Friction and wear characteristics are affected by coating defects, since the large nodules are pulled out and additional wear debris is generated.

Annular illumination is effective in enhancing the depth of focus for scanningelectron microscopes (SEMs). However, owing to high side lobes of the point-spread function (PSF), annular illumination results in poor image sharpness. The conventional deconvolution method, which converts the PSF to a delta function, can improve image sharpness, but results in artifacts due to noise amplification. In this paper, we propose an image processing method that can reduce the deterioration of image sharpness. With this method, the PSF under annular illumination is converted to that under standard illumination. Through simulations, we verified that the image sharpness of SEM images under annular illumination with the proposed method can be improved without noise amplification.

In this study, we succeeded in acquiring scanningelectron microscope (SEM) images of carbon nanotube (CNT) derivatives with different surface properties based on an electro-conductive pretreatment using a room temperature ionic liquid (IL). The quality of the obtained SEM images depended on their surface properties and the hydrophilicities of IL used. When the hydrophilicities of both the sample surface and the IL were close, the obtained SEM images had a high resolution. In contrast, SEM imges of samples pretreated with an IL, which had different hydrophilicities from the sample, was observed with low resolution and low quality. This result suggests that the relationship between both hydrophilicities is the dominant factor for this visualization method. PMID:26726681

The ongoing scientific debate as to whether or not the Martian meteorite ALH84001 contained evidence of possible biogenic activities showed the need to establish consistent methods to ascertain the origin of such evidence. To distinguish between terrestrial organic material/microbial contaminants and possible indigenous microbiota within meteorites is therefore crucial. With this in mind a depth profile consisting of four samples from a new sample allocation of Martian meteorite Nakhla was investigated using scanningelectron microscopy (SEM) and energy dispersive X-ray analysis. SEM imaging of freshly broken fractured chips revealed structures strongly recent terrestrial microorganisms, in some cases showing evidence of active growth. This conclusion was supported by EDX analysis, which showed the presence of carbon associated with these structures, we concluded that these structures represent recent terrestrial contaminants rather than structures indigenous to the meteorite. Page

An automated two-degree-of-freedom specimen positioning stage has been developed at the NASA Glenn Research Center to map and monitor defects in fatigue specimens. This system expedites the examination of the entire gauge section of fatigue specimens so that defects can be found using scanningelectron microscopy (SEM). Translation and rotation stages are driven by microprocessor-based controllers that are, in turn, interfaced to a computer running custom-designed software. This system is currently being used to find and record the location of ceramic inclusions in powder metallurgy materials. The mapped inclusions are periodically examined during interrupted fatigue experiments. The number of cycles to initiate cracks from these inclusions and the rate of growth of initiated cracks can then be quantified. This information is necessary to quantify the effect of this type of defect on the durability of powder metallurgy materials. This system was developed with support of the Ultra Safe program.

Scanningelectron-microscope (SEM) has been successfully applied to CD measurement as promising tools for qualifying and controlling quality of semiconductor devices in in-line manufacturing process since 1985. Furthermore SEM is proposed to be applied to in-die overlay monitor in the local area which is too small to be measured by optical overlay measurement tools any more, when the overlay control limit is going to be stringent and have un-ignorable dependence on device pattern layout, in-die location, and singular locations in wafer edge, etc. In this paper, we proposed new overlay measurement and inspection system to make an effective use of in-line SEM image, in consideration of trade-off between measurement uncertainty and measurement pattern density in each SEM conditions. In parallel, we make it clear that the best hybrid overlay metrology is in considering each tool's technology portfolio.

The ability of scanningelectron acoustic microscopy (SEAM) to characterize ceramic materials is assessed. SEAM images of Vickers indentations in SiC whisker-reinforced alumina clearly reveal not only the radial cracks, the length of which can be used to estimate the fracture toughness of the material, but also reveal strong contrast, interpreted as arising from the combined effects of lateral cracks and the residual stress field left in the SiC whisker-reinforced alumina by the indenter. The strong contrast is removed after the material is heat treated at 1000 C to relieve the residual stresses around the indentations. A comparison of these observations with SEAM and reflected polarized light observations of Vickers indentations in soda-lime glass both before and after heat treatment confirms the interpretation of the strong contrast.

By using environmental scanningelectron microscopy, the morphological changes of Vero cells attached to and grown on the microcarrier Cytodex-3 were observed, and their behavior of adhesion, spreading and proliferation was analyzed. The effect of exogenous fibronectin/ laminin on adhesion and spreading of MCC/Vero cell was studied. The images of ESEM showed that expansion of cell growth was directed toward vacancy space. The growth curve and cell concentration change during the whole culture process were obtained from the statistical counting method based on ESEM images and the crystal violet method. The growth rate of Vero cells increases with increasing the concentration of cell inoculation, that is, the specific growth rate increases quickly with increasing the concentration of cell inoculation. When serum concentration in medium #199 ranged from 5% to 10%, experimental results indicated that serum concentration is one of the important factors influencing cell growth, particularly in the cell adhesion and spreading stage. PMID:18763074

Damage scar volume measurements taken from like metal fretting pairs combined with scanningelectron microscopy observations showed that three sequentially operating mechanisms result in the fretting of titanium, Monel-400, and cobalt - 25-percent molybdenum. Initially, adhesion and plastic deformation of the surface played an important role. This was followed after a few hundred cycles by a fatigue mechanism which produced spall-like pits in the damage scar. Finally, a combination of oxidation and abrasion by debris particles became most significant. Damage scar measurements made on several elemental metals after 600,000 fretting cycles suggested that the ratio of oxide hardness to metal hardness was a measure of the susceptibility of a metal to progressive damage by fretting.

A novel type of colonisation of a basaltic rock, collected on the Arctic island of Svalbard, Norway, during the AMASE expedition in 2004, was characterised using Raman spectroscopy and ScanningElectron Microscopy (SEM). The sample contains two different types of extremophile communities, one occurring behind a radial white crystallisation and the other occurring inside a dark vacuole. Several types of minerals and microbial colonies have been identified by both Raman spectroscopy and SEM analyses. It is the first time that photosynthetic communities have been documented to colonise the inside of dark basaltic rocks. Our discovery has important implications for planetary exploration because it extends the analytical capability and our understanding of microbial rock colonisations to subaerial volcanic outcrops and has wide implications towards the search for life in extraterrestrial planets. In this work we also demonstrate that the use of different laser wavelengths for Raman spectroscopic studies and complementary microscopic analysis are critical for a comprehensive organic and inorganic compound identification.

Minimization of uncertainty is essential to extend the usable range of the 15-psid ElectronicallyScanned Pressure [ESP) transducer measurements to the low free-stream static pressures found in hypersonic wind tunnels. Statistical characterization of environmental error sources inducing much of this uncertainty requires a well defined and controlled calibration method. Employing such a controlled calibration system, several studies were conducted that provide quantitative information detailing the required controls needed to minimize environmental and human induced error sources. Results of temperature, environmental pressure, over-pressurization, and set point randomization studies for the 15-psid transducers are presented along with a comparison of two regression methods using data acquired with both 0.36-psid and 15-psid transducers. Together these results provide insight into procedural and environmental controls required for long term high-accuracy pressure measurements near 0.01 psia in the hypersonic testing environment using 15-psid ESP transducers.

Minimization of uncertainty is essential to extend the usable range of the 15-psid ElectronicallyScanned Pressure (ESP) transducer measurements to the low free-stream static pressures found in hypersonic wind tunnels. Statistical characterization of environmental error sources inducing much of this uncertainty requires a well defined and controlled calibration method. Employing such a controlled calibration system, several studies were conducted that provide quantitative information detailing the required controls needed to minimize environmental and human induced error sources. Results of temperature, environmental pressure, over-pressurization, and set point randomization studies for the 15-psid transducers are presented along with a comparison of two regression methods using data acquired with both 0.36-psid and 15-psid transducers. Together these results provide insight into procedural and environmental controls required for long term high-accuracy pressure measurements near 0.01 psia in the hypersonic testing environment using 15-psid ESP transducers.

The aim of this study was to verify that the combination of focused ion beam (FIB) and scanningelectron microscope/energy-dispersive X-ray (SEM/EDX) could be applied to determine the sequence of line crossings. The samples were transferred into FIB/SEM for FIB milling and an imaging operation. EDX was able to explore the chemical components and the corresponding elemental distribution in the intersection. The technique was successful in determining the sequence of heterogeneous line intersections produced using gel pens and red sealing ink with highest success rate (100% correctness). These observations show that the FIB/SEM was the appropriate instrument for an overall examination of document. PMID:27122423

This report describes conceptual thermal design study for an ElectronicallyScanned Thinned Array Radiometer (ESTAR). ESTAR is an instrument concept for the measurement of soil moisture from space using synthetic aperture radiometry. The thermal design goal is to minimize the orbital temperature variation of the radiometer receivers using established materials and techniques. Two design approaches have been investigated; the first uses the waveguide as a heat sink, and the second uses a nadir facing radiator on the receiver assembly. The second approach minimizes the receiver's impact on the waveguide temperatures. Predicted temperatures for all receivers are presented for the two cases indicating the transient thermal environments the receivers would experience during an orbit. In addition, the effects of the receiver heat dissipation on the waveguide temperatures are shown.

Application of electronicscanning to a sequence of coherence-multiplexed strain sensors is proposed in this paper. The sensors consist of a cascade of HB fibers spliced with their polarization axes rotated by certain angles. We theoretically analyzed the behavior of such chains as a function of their alignment and found the optimal alignment ensuring readout of every sensor with the maximum S/N ratio. The performance of parallel and serial multiplexing configurations was experimentally studied. As a receiving interferometer we used a Wollaston prism followed by a CCD camera and an image processing system while a stepped delay line made of calcite and crystalline quartz was used to match the group delays between sensing and receiving interferometers.

Traditional embryology courses demand considerable expenditure of time and effort from students to master the spatial awareness skills necessary to create three-dimensional mental images from two-dimensional serial sections. Then students must imagine a movie sequence of the changes which take place during normal development. Further steps are required to relate this information to the clinical situation. As more medical and dental schools move towards problem-based curricula, more efficient methods of improving understanding of embryology are needed. The development of many organs can be studied using scanningelectron micrographs of embryos at different ages. These high quality images are more easily interpreted by our students than histological sections and the understanding achieved more readily applied to clinical problems. Still more beneficial would be the provision of moving images showing the actual changes happening. We decided to use computer morphing techniques to prepare movie sequences showing development of the face and plate. For each, four scanningelectron micrographs of appropriately-sized sheep embryo heads were taken at the same magnification and orientation to use as start and end points of morphing sequences. After using retouching techniques to colour the separate processes, further sequences were prepared. The discipline of maintaining the same magnification throughout and the possibility of directly observing changes between stages revealed some surprising growth patterns. This technique is adaptable to any area of biological development where pre- and post-illustrations are available. Animations can be presented on computer or on video and incorporated into programs. Student feedback has been very favourable. PMID:8983113

Background Endodontic therapy is considered a series of important and interdependent steps, and failure of any of these steps may compromise the treatment outcome. This study aimed to evaluate the effectiveness of three different rotary systems in removing obturation materials during endodontic retreatment using scanningelectron microscopy (SEM) analysis. Material and Methods Thirty-six endodontically treated teeth were selected and divided into 3 groups of 10 and 1 control group with 6 dental elements. The groups were divided according to the rotary system used for removing gutta-percha, as follows: G1: ProTaper system; G2: K3 system; G3: Mtwo system; and G4: Control group. Thereafter, the roots were split and the sections were observed under SEM, for analysis and counting of clear dentinal tubules, creating the variable “degree of dentinal tubule patency” (0: intensely clear; 1: moderately clear; 2: slightly clear; 3: completely blocked). The data were subjected to the Friedman and Kruskal-Wallis statistical tests. Results No differences were observed in the “degree of dentinal tubule patency” neither between the root thirds (to each evaluated group) nor between the groups (to each evaluated third). Nevertheless, when the three root thirds were grouped (providing evaluation of all root extension), the “degree of dentinal tubule patency” was lower in G1 than in G3 (p<0.05), but showed no differences neither between G1 and G2 nor G2 and G3. Conclusions No technique was able to completely remove the canal obturation material, despite G1 having shown better results, although without significant difference to G2 Key words:Scanningelectron microscopy, NiTi, retreatment. PMID:27034750

Analysis of acute cellular changes seen in nasal mucosa of Wistar-Albino rats exposed to different doses of oleoresin capsicum for various time periods by means of scanningelectron microscopy. Thirty-five Wistar-Albino rats were divided into five groups of seven rats each. 6-gram oleoresin capsicum per second was sprayed into cages of the groups except group 1. Spray times and duration of exposure to pepper gasses were different for each group. Thirty minutes after the exposure, the animals were killed and specimens from their nasal mucosas were harvested and examined under scanningelectron microscope. Mucosal damage was scored from 0-4 points. Mean values of nasal mucosa damage scores of the groups were calculated and compared statistically. Average damage scores of the groups exposed to identical doses of oleoresin capsicum for various exposure times were compared and a statistically significant difference was seen between Groups 2 and 3 (p < 0.05), however the difference between Groups 4 and 5 was insignificant (p > 0.05). Average damage scores of the groups exposed to various doses for identical exposure times were compared, and statistically significant differences were observed between Groups 2 and 4 and also Groups 3 and 5 (p < 0.05). Outcomes of our study have demonstrated that pepper gas exerts destructive changes on rat nasal mucosa. The extent of these destructive changes increases with the prolonged exposure to higher doses. Besides, exposure time also stands out as an influential factor on the extent of the destructive changes. PMID:24627077

We have used a combination of lead isotopes and scanningelectron microscopy to determine the relationships between different exhibits in a murder case. Samples involved lead projectiles removed from the deceased's head and a pillow, lead-rich scrapings and particles (gunshot residues) from spent cartridges and a silencer, and particles from a pillowcase. The lead projectiles had the same isotopic composition. with the lead being derived from the same dominantly geologically old source(s). The lead smear from the silencer had the same isotopic composition as the projectiles, and the lead was probably from the same source. The particles from the spent cartridges had varying elemental compositions ranging from PbO to PbCuZn +/- Ba with or without Si and are consistent with derivation from the primer. The lead isotopic compositions of the particles from the spent cartridges show some variations, but these are markedly different from those of the projectiles, indicating lead from a mixture of geologically old and geologically young lead. The particles from the pillowcase were extremely small (usually <50 microm size) and showed varying isotopic compositions, some consistent with the gunshot residue from the cartridges. As the exhibits had been handled extensively prior to the present investigation, including some being sent to North America, there is a high likelihood that handling was not done in clean room environments and may have been contaminated. In this instance, as we were concerned about contamination, especially of the pillowcase, we felt contamination negated use of the results for assistance in proving the innocence or guilt of the accused. A combination of high-precision lead isotope measurements with scanningelectron microscopy provides a powerful tool for forensic investigations if precautions are taken in handling the exhibits. PMID:12353538

Low-temperature scanningelectron microscopy (SEM) was used to observe metamorphosed snow, glacial firn, and glacial ice obtained from South Cascade Glacier in Washington State, USA. Biotic samples consisting of algae (Chlamydomonas nivalis) and ice worms (a species of oligochaetes) were also collected and imaged. In the field, the snow and biological samples were mounted on copper plates, cooled in liquid nitrogen, and stored in dry shipping containers which maintain a temperature of -196??C. The firn and glacier ice samples were obtained by extracting horizontal ice cores, 8 mm in diameter, at different levels from larger standard glaciological (vertical) ice cores 7.5 cm in diameter. These samples were cooled in liquid nitrogen and placed in cryotubes, were stored in the same dry shipping container, and sent to the SEM facility. In the laboratory, the samples were sputter coated with platinum and imaged by a low-temperature SEM. To image the firn and glacier ice samples, the cores were fractured in liquid nitrogen, attached to a specimen holder, and then imaged. While light microscope images of snow and ice are difficult to interpret because of internal reflection and refraction, the SEM images provide a clear and unique view of the surface of the samples because they are generated from electrons emitted or reflected only from the surface of the sample. In addition, the SEM has a great depth of field with a wide range of magnifying capabilities. The resulting images clearly show the individual grains of the seasonal snowpack and the bonding between the snow grains. Images of firn show individual ice crystals, the bonding between the crystals, and connected air spaces. Images of glacier ice show a crystal structure on a scale of 1-2 mm which is considerably smaller than the expected crystal size. Microscopic air bubbles, less than 15 ??m in diameter, clearly marked the boundaries between these crystal-like features. The life forms associated with the glacier were

Confocal microscopy imaging of cells allows to visualize the presence of specific antigens by using fluorescent tags or fluorescent proteins, with resolution of few hundreds of nanometers, providing their localization in a large field-of-view and the understanding of their cellular function. Conversely, in scanningelectron microscopy (SEM), the surface morphology of cells is imaged down to nanometer scale using secondary electrons. Combining both imaging techniques have brought to the correlative light and electron microscopy, contributing to investigate the existing relationships between biological surface structures and functions. Furthermore, in SEM, backscattered electrons (BSE) can image local compositional differences, like those due to nanosized gold particles labeling cellular surface antigens. To perform SEM imaging of cells, they could be grown on conducting substrates, but obtaining images of limited quality. Alternatively, they could be rendered electrically conductive, coating them with a thin metal layer. However, when BSE are collected to detect gold-labeled surface antigens, heavy metals cannot be used as coating material, as they would mask the BSE signal produced by the markers. Cell surface could be then coated with a thin layer of chromium, but this results in a loss of conductivity due to the fast chromium oxidation, if the samples come in contact with air. In order to overcome these major limitations, a thin layer of indium-tin-oxide was deposited by ion-sputtering on gold-decorated HeLa cells and neurons. Indium-tin-oxide was able to provide stable electrical conductivity and preservation of the BSE signal coming from the gold-conjugated markers. PMID:25810353

A maskless and programmable direct electron beam writing method is reported for making high-precision superhydrophilic-superhydrophobic wetting patterns with 152° contact angle contrast using an environmental scanningelectron microscope (ESEM). The smallest linewidth achieved is below 1 μm. The reported effects of the electron beam induced local plasma may also influence a variety of microscopic wetting studies in ESEM. PMID:26880568

I explore the behavior of a nanoscale device known as the single-electron transistor (SET). Using e-beam lithography and conventional double-angle evaporation, I have fabricated Al/AlO x/Al single-electron transistors (SETs) and studied their behavior from 85 mK to 5 K. The total island capacitance CSigma of the devices ranged from 120 to 200 aF with typical estimated junction overlaps of about 30 nm x 30 nm. At 4.2 K, my devices displayed well-behaved I-Vg characteristics with the maximum charge-transfer function ∂I/∂Qo ranging from 4 to 130 pA/e. The electrical characteristics of these devices agreed well with the Orthodox Theory, with current modulation being observed up to a temperature T ≅ e 2/(2CSigmakb). Also, I studied random-telegraph charge fluctuations in an SET. I measured the fluctuations from 85 mK to 3 K and observed that the SET switched between two states, causing charge shifts of DeltaQo = 0.1 +/- 0.025 e on the SET's island. The transition rate out of each state was periodic in the gate voltage, varied non-monotonically with the device bias voltage, and was independent of the temperature below about 0.3 K. I discuss two effects that could contribute to the behavior of the transition rates, including heating of the defect by the island conduction electrons and inelastic scattering between the defect and the electrons flowing through the SET. I also measured the temperature dependence of the charge noise power spectral density Sq in several SETs from 85 mK to 4 K. Although individual Lorentzians were often visible, the noise spectra were dominated by excess low-frequency noise with a power-law dependence on frequency f where Sq ∝ 1/ fbeta and beta ≅ 1. Below about 0.5 K, Sq were weakly dependent on the temperature T . Above 1 K, the charge noise Sq increased with T, and at 4 K Sq ≈ 10 -4 e2/Hz at 1 Hz, about a factor of 100 greater than at 85 mK. Finally, I present the design of a scanning single-electron transistor microscope which

X-ray crystallography requires high quality crystals above a given size. This requirement not only limits the proteins to be analyzed, but also reduces the speed of the structure determination. Indeed, the tertiary structures of many physiologically important proteins remain elusive because of the so-called "crystallization bottleneck". Once microcrystals have been obtained, crystallization conditions can be optimized to produce bigger and better crystals. However, the identification of microcrystals can be difficult due to the resolution limit of optical microscopy. Electron microscopy has sometimes been utilized instead, with the disadvantage that the microcrystals usually must be observed in vacuum, which precludes the usage for crystal screening. The atmospheric scanningelectron microscope (ASEM) allows samples to be observed in solution. Here, we report the use of this instrument in combination with a special thin-membrane dish with a crystallization well. It was possible to observe protein crystals of lysozyme, lipase B and a histone chaperone TAF-Iβ in crystallization buffers, without the use of staining procedures. The smallest crystals observed with ASEM were a few μm in width, and ASEM can be used with non-transparent solutions. Furthermore, the growth of salt crystals could be monitored in the ASEM, and the difference in contrast between salt and protein crystals made it easy to distinguish between these two types of microcrystals. These results indicate that the ASEM could be an important new tool for the screening of protein microcrystals. PMID:22949879

Selectively capturing the ultrafast dynamics of charge carriers on materials surfaces and at interfaces is crucial to the design of solar cells and optoelectronic devices. Despite extensive research efforts over the past few decades, information and understanding about surface-dynamical processes, including carrier trapping and recombination remains extremely limited. A key challenge is to selectively map such dynamic processes, a capability that is hitherto impractical by time-resolved laser techniques, which are limited by the laser's relatively large penetration depth and consequently these techniques record mainly bulk information. Such surface dynamics can only be mapped in real space and time by applying four-dimensional (4D) scanning ultrafast electron microscopy (S-UEM), which records snapshots of materials surfaces with nanometer spatial and subpicosecond temporal resolutions. In this method, the secondary electron (SE) signal emitted from the sample's surface is extremely sensitive to the surface dynamics and is detected in real time. In several unique applications, we spatially and temporally visualize the SE energy gain and loss, the charge carrier dynamics on the surface of InGaN nanowires and CdSe single crystal and its powder film. We also discuss the mechanisms for the observed dynamics, which will be the foundation for future potential applications of S-UEM to a wide range of studies on material surfaces and device interfaces. PMID:26911313

We describe rare-earth-doped nanophosphors (RE-NPs) for biological imaging using cathodoluminescence(CL) microscopy based on scanning transmission electron microscopy (STEM). We report the first demonstration of multicolor CL nanobioimaging using STEM with nanophosphors. The CL spectra of the synthesized nanophosphors (Y2O3∶Eu, Y2O3∶Tb) were sufficiently narrow to be distinguished. From CL images of RE-NPs on an elastic carbon-coated copper grid, the spatial resolution was beyond the diffraction limit of light.Y2O3∶Tb and Y2O3∶Eu RE-NPs showed a remarkable resistance against electron beam exposure even at high acceleration voltage (80 kV) and retained a CL intensity of more than 97% compared with the initial intensity for 1 min. In biological CL imaging with STEM, heavy-metal-stained cell sections containing the RE-NPs were prepared,and both the CL images of RE-NPs and cellular structures, such as mitochondria, were clearly observed from STEM images with high contrast. The cellular CL imaging using RE-NPs also had high spatial resolution even though heavy-metal-stained cells are normally regarded as highly scattering media. Moreover, since theRE-NPs exhibit photoluminescence (PL) excited by UV light, they are useful for multimodal correlative imaging using CL and PL. PMID:26000793

NASA Marshall Space Flight Center (MSFC) is leading an effort to develop a Miniaturized Variable Pressure ScanningElectron Microscope (MVP-SEM) for in-situ imaging and chemical analysis of uncoated samples. This instrument development will be geared towards operation on Mars and builds on a previous MSFC design of a mini-SEM for the moon (funded through the NASA Planetary Instrument Definition and Development Program). Because Mars has a dramatically different environment than the moon, modifications to the MSFC lunar mini-SEM are necessary. Mainly, the higher atmospheric pressure calls for the use of an electron gun that can operate at High Vacuum, rather than Ultra-High Vacuum. The presence of a CO2-rich atmosphere also allows for the incorporation of a variable pressure system that enables the in-situ analysis of nonconductive geological specimens. Preliminary testing of Mars meteorites in a commercial Environmental SEM(Tradmark) (FEI) confirms the usefulness of lowcurrent/low-accelerating voltage imaging and highlights the advantages of using the Mars atmosphere for environmental imaging. The unique capabilities of the MVP-SEM make it an ideal tool for pursuing key scientific goals of NASA's Flagship Mission Max-C; to perform in-situ science and collect and cache samples in preparation for sample return from Mars.

A number of shock-recovery experiments have been performed on Berea sandstone for different conditions: dry, water-saturated, hydrostatically water-pressurized and Helium gas-pressurized. The authors also conducted experiments with purified quartz sand in dry and water-saturated conditions with a grain size between 212 to 250 {micro}m and 250 to 300 {micro}m to compare with damaged Berea sandstone. The shock stresses in the range between 1.2 to 9.8 GPa were achieved by impacting projectiles accelerated by a single-stage light-gas gun. Different flyer plate thicknesses were used to produce different shock pulse durations. The water-pressurized sandstone targets were hydrostatically pressurized between 7.58-7.79 MPa, whereas the gas-pressure samples were pressurized to 27.5 MPa using helium gas. The microstructural damage of all specimens is being investigated by using scanningelectron microscopy (SEM) in order to determine differences for these conditions. In this report they will present the results of the systematic SEM investigations for each experiment. The scientific results and discussions including X-ray computed micro tomography and statistical analysis are presented elsewhere. Overall, they collected around 1600 SEM pictures, which are available in electronic form on Compact Disks (CDs). They also provide the results of the laser particle analysis on the CDs.

Biofilms are complex communities of microbes that attach to biotic or abiotic surfaces causing chronic infectious diseases. Within a biofilm, microbes are embedded in a self-produced soft extracellular matrix (ECM), which protects them from the host immune system and antibiotics. The nanoscale visualisation of delicate biofilms in liquid is challenging. Here, we develop atmospheric scanningelectron microscopy (ASEM) to visualise Gram-positive and -negative bacterial biofilms immersed in aqueous solution. Biofilms cultured on electron-transparent film were directly imaged from below using the inverted SEM, allowing the formation of the region near the substrate to be studied at high resolution. We visualised intercellular nanostructures and the exocytosis of membrane vesicles, and linked the latter to the trafficking of cargos, including cytoplasmic proteins and the toxins hemolysin and coagulase. A thick dendritic nanotube network was observed between microbes, suggesting multicellular communication in biofilms. A universal immuno-labelling system was developed for biofilms and tested on various examples, including S. aureus biofilms. In the ECM, fine DNA and protein networks were visualised and the precise distribution of protein complexes was determined (e.g., straight curli, flagella, and excreted cytoplasmic molecular chaperones). Our observations provide structural insights into bacteria-substratum interactions, biofilm development and the internal microbe community. PMID:27180609

Erythroblastic islands are multicellular clusters in which a central macrophage supports the development and maturation of red blood cell (erythroid) progenitors. These clusters play crucial roles in the pathogenesis observed in animal models of hematological disorders. The precise structure and function of erythroblastic islands is poorly understood. Here, we have combined scanningelectron microscopy and immuno-gold labeling of surface proteins to develop a better understanding of the ultrastructure of these multicellular clusters. The erythroid-specific surface antigen Ter-119 and the transferrin receptor CD71 exhibited distinct patterns of protein sorting during erythroid cell maturation as detected by immuno-gold labeling. During electron microscopy analysis we observed two distinct classes of erythroblastic islands. The islands varied in size and morphology, and the number and type of erythroid cells interacting with the central macrophage. Assessment of femoral marrow isolated from a cavid rodent species (guinea pig, Cavis porcellus) and a marsupial carnivore species (fat-tailed dunnarts, Sminthopsis crassicaudata) showed that while the morphology of the central macrophage varied, two different types of erythroblastic islands were consistently identifiable. Our findings suggest that these two classes of erythroblastic islands are conserved in mammalian evolution and may play distinct roles in red blood cell production. PMID:26898901

Use of focused ion-beam scanningelectron microscopy (FIB-SEM) to investigate the internal composition of atmospheric particles is demonstrated for assessing particle optical properties. In the FIB-SEM instrument equipped with an X-ray detector, a gallium-ion beam mills the particle, while the electron beam images the slice faces and energy-dispersive X-ray spectroscopy provides element maps of the particle. Differences in assessments of optical behavior based on FIB-SEM and conventional SEM were shown for five selected urban dust particles. The benefit of FIB-SEM for accurately determining the depth and size of optically important phases within particles was shown. FIB-SEM revealed that iron oxide grains left undetected by conventional SEM could potentially shift the single-scattering albedo of the particle from negative to positive radiative forcing. Analysis of a coke-like particle showed that 73% of the light-scattering inclusion went undetected with conventional SEM, causing the bulk absorption coefficient to vary by as much as 25%. Optical property calculations for particles as volume-equivalent spheres and as spheroids that approximated actual particle shapes revealed that the largest effect between conventional SEM and FIB-SEM analyses was on backscattering efficiency, in some cases varying several-fold. PMID:23763344

Biofilms are complex communities of microbes that attach to biotic or abiotic surfaces causing chronic infectious diseases. Within a biofilm, microbes are embedded in a self-produced soft extracellular matrix (ECM), which protects them from the host immune system and antibiotics. The nanoscale visualisation of delicate biofilms in liquid is challenging. Here, we develop atmospheric scanningelectron microscopy (ASEM) to visualise Gram-positive and -negative bacterial biofilms immersed in aqueous solution. Biofilms cultured on electron-transparent film were directly imaged from below using the inverted SEM, allowing the formation of the region near the substrate to be studied at high resolution. We visualised intercellular nanostructures and the exocytosis of membrane vesicles, and linked the latter to the trafficking of cargos, including cytoplasmic proteins and the toxins hemolysin and coagulase. A thick dendritic nanotube network was observed between microbes, suggesting multicellular communication in biofilms. A universal immuno-labelling system was developed for biofilms and tested on various examples, including S. aureus biofilms. In the ECM, fine DNA and protein networks were visualised and the precise distribution of protein complexes was determined (e.g., straight curli, flagella, and excreted cytoplasmic molecular chaperones). Our observations provide structural insights into bacteria-substratum interactions, biofilm development and the internal microbe community. PMID:27180609

The aim of this paper is to describe an optimized methodology to study the surface characteristics and internal structure of biopolymer capsules using scanningelectron microscopy (SEM) in environmental mode. The main advantage of this methodology is that no preparation is required and, significantly, no metallic coverage is deposited on the surface of the specimen, thus preserving the original capsule shape and its surface morphology. This avoids introducing preparation artefacts which could modify the capsule surface and mask information concerning important feature like porosities or roughness. Using this method gelatin and mainly fatty coatings, difficult to be analyzed by standard SEM technique, unambiguously show fine details of their surface morphology without damage. Furthermore, chemical contrast is preserved in backscattered electron images of unprepared samples, allowing visualizing the internal organization of the capsule, the quality of the envelope, etc... This study provides pointers on how to obtain optimal conditions for the analysis of biological or sensitive material, as this is not always studied using appropriate techniques. A reliable evaluation of the parameters used in capsule elaboration for research and industrial applications, as well as that of capsule functionality is provided by this methodology, which is essential for the technological progress in this domain. PMID:25492208

A method of direct visualization of cell organelles by scanningelectron microscopy (SEM) is described. Plant and animal tissues fixed in glutaraldehyde and osmium tetroxide are treated with the ligand thiocarbohydrazide and a second osmium tetroxide solution, to increase their osmium content. Tissues are then dehydrated, infiltrated with an epoxy monomer, and together solidified with dry ice and fractured. The pieces are transferred to pure acetone, critical-point dried, attached to stubs with silver paint and viewed by SEM. The ligating procedure increases the osmium concentration at its original bonding site sufficiently to render the tissue electrically conductive, thus obviating the need for metallic coating. he organelles at the fractured surface are revaled in relation to their osmium incorporation rather than by surface irregularities as with coating methods. The image derived from the uncoated surface approaches in resolution that of transmission electron micrographs of thin sections. A protion of the image arising from a small distance below the surface, while at progressively lower resolution, provides some 3-dimensional information about cell fine structure. PMID:777015

Collecting phylogenetic information simultaneously with mineral textures and associations for geomicrobiological studies has always been a challenge. Recently a new type of nucleotide reporter system has been developed that utilizes small particles of nanogold (1.4 nm) covalently attached to oligonucelotide probes. Due to the small size and electron density of these nanogold reporter molecules, this in situ hybridization technique allows for the phylogenetic identification of microbial targets with a scanningelectron microscope. Here we present new applications of the nanogold hybridization technique for pure cultures and natural microbial communities in a range of geologic samples including sand grains, basalt chips incubated on deep sea hydrothermal vents, and gypsum crusts sampled from a saline lake. While we do observe nonspecific binding of nanogold probes to minerals and organic compounds in geologic matrices, this can be distinguished from positive hybridization events with a spatial variety analysis. To assess the potential of nanogold hybridizations for quantitative assessments of microbial communities, fluorescent in situ hybridizations (FISH) were performed on all samples and compared to cell counts generated from nanogold hybridizations.

A field emission scanningelectron microscopy (FESEM) method was developed to assess the stability of a recombinant adenovirus (rAd). This method was designed to simultaneously sort, count, and size the total number of rAd viral species observed within an image field. To test the method, a preparation of p53 transgene-expressing recombinant adenovirus (rAd/p53) was incubated at 37 degrees C and the viral particles were evaluated by number, structure, and degree of aggregation as a function of time. Transmission electron microscopy (TEM) was also used to obtain ultrastructural detail. In addition, the infectious activity of the incubated rAd/p53 samples was determined using flow cytometry. FESEM image-analysis revealed that incubation at 37 degrees C resulted in a time-dependent decrease in the total number of detectable single rAd/p53 virus particles and an increase in apparent aggregates composed of more than three adenovirus particles. There was also an observed decrease in both the diameter and perimeter of the single rAd/p53 viral particles. TEM further revealed the accumulation of damaged single particles with time at 37 degrees C. The results of this study demonstrate that FESEM, coupled with sophisticated image analysis, may be an important tool in quantifying the distribution of aggregated species and assessing the overall stability of rAd samples. PMID:12396622

We describe rare-earth-doped nanophosphors (RE-NPs) for biological imaging using cathodoluminescence (CL) microscopy based on scanning transmission electron microscopy (STEM). We report the first demonstration of multicolor CL nanobioimaging using STEM with nanophosphors. The CL spectra of the synthesized nanophosphors (Y2O3:Eu, Y2O3:Tb) were sufficiently narrow to be distinguished. From CL images of RE-NPs on an elastic carbon-coated copper grid, the spatial resolution was beyond the diffraction limit of light. Y2O3:Tb and Y2O3:Eu RE-NPs showed a remarkable resistance against electron beam exposure even at high acceleration voltage (80 kV) and retained a CL intensity of more than 97% compared with the initial intensity for 1 min. In biological CL imaging with STEM, heavy-metal-stained cell sections containing the RE-NPs were prepared, and both the CL images of RE-NPs and cellular structures, such as mitochondria, were clearly observed from STEM images with high contrast. The cellular CL imaging using RE-NPs also had high spatial resolution even though heavy-metal-stained cells are normally regarded as highly scattering media. Moreover, since the RE-NPs exhibit photoluminescence (PL) excited by UV light, they are useful for multimodal correlative imaging using CL and PL.

X-ray crystallography requires high quality crystals above a given size. This requirement not only limits the proteins to be analyzed, but also reduces the speed of the structure determination. Indeed, the tertiary structures of many physiologically important proteins remain elusive because of the so-called “crystallization bottleneck”. Once microcrystals have been obtained, crystallization conditions can be optimized to produce bigger and better crystals. However, the identification of microcrystals can be difficult due to the resolution limit of optical microscopy. Electron microscopy has sometimes been utilized instead, with the disadvantage that the microcrystals usually must be observed in vacuum, which precludes the usage for crystal screening. The atmospheric scanningelectron microscope (ASEM) allows samples to be observed in solution. Here, we report the use of this instrument in combination with a special thin-membrane dish with a crystallization well. It was possible to observe protein crystals of lysozyme, lipase B and a histone chaperone TAF-Iβ in crystallization buffers, without the use of staining procedures. The smallest crystals observed with ASEM were a few μm in width, and ASEM can be used with non-transparent solutions. Furthermore, the growth of salt crystals could be monitored in the ASEM, and the difference in contrast between salt and protein crystals made it easy to distinguish between these two types of microcrystals. These results indicate that the ASEM could be an important new tool for the screening of protein microcrystals. PMID:22949879

Scanning transmission electron microscopy (STEM) has been widely used for characterization of materials; to identify micro- and nano-structures within a sample and to analyze crystal and defect structures. High-angle annular dark field (HAADF) STEM imaging using atomic number (Z) contrast has proven capable of resolving atomic structures with better than 2 A lateral resolution. In this work, the HAADF STEM imaging mode is used in combination with multislice simulations. This combination is applied to the investigation of the temperature dependence of the intensity collected by the HAADF detector in silicon, and to convergent beam electron diffraction (CBED) to measure the degree of chemical order in intermetallic nanoparticles. The experimental and simulation results on the high-angle scattering of 300 keV electrons in crystalline silicon provide a new contribution to the understanding of the temperature dependence of the HAADF intensity. In the case of 300 keV, the average high-angle scattered intensity slightly decreases as the temperature increases from 100 K to 300 K, and this is different from the temperature dependence at 100 keV and 200 keV where HAADF intensity increases with temperature, as had been previously reported by other workers. The L10 class of hard magnetic materials has attracted continuous attention as a candidate for high-density magnetic recording media, as this phase is known to have large magnetocrystalline anisotropy, with magnetocrystalline anisotropy constant, Ku, strongly dependent on the long-range chemical order parameter, S. A new method is developed to assess the degree of chemical order in small FePt L1 0 nanoparticles by implementing a CBED diffraction technique. Unexpectedly, the degree of order of individual particles is highly variable and not a simple function of particle size or sample composition. The particle-to-particle variability observed is an important new aspect to the understanding of phase transformations in

Lattice, charge, orbital, and spin are the four fundamental degrees of freedom in condensed matter, of which the interactive coupling derives tremendous novel physical phenomena, such as high-temperature superconductivity (high-T c SC) and colossal magnetoresistance (CMR) in strongly correlated electronic system. Direct experimental observation of these freedoms is essential to understanding the structure-property relationship and the physics behind it, and also indispensable for designing new materials and devices. Scanning transmission electron microscopy (STEM) integrating multiple techniques of structure imaging and spectrum analysis, is a comprehensive platform for providing structural, chemical and electronic information of materials with a high spatial resolution. Benefiting from the development of aberration correctors, STEM has taken a big breakthrough towards sub-angstrom resolution in last decade and always steps forward to improve the capability of material characterization; many improvements have been achieved in recent years, thereby giving an in-depth insight into material research. Here, we present a brief review of the recent advances of STEM by some representative examples of perovskite transition metal oxides; atomic-scale mapping of ferroelectric polarization, octahedral distortions and rotations, valence state, coordination and spin ordering are presented. We expect that this brief introduction about the current capability of STEM could facilitate the understanding of the relationship between functional properties and these fundamental degrees of freedom in complex oxides. Project supported by the National Key Basic Research Project, China (Grant No. 2014CB921002), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB07030200), and the National Natural Science Foundation of China (Grant Nos. 51522212 and 51421002).

Due to their large specific surface and their abundance, micro and nano particles play an important role in the transport of micropollutants in the environment. Natural particles are usually composed of a mixture of inorganic amorphous or crystalline material (mainly FeOOH, Fe(x)Oy, Mn(x)Oy and clays) and organic material (humics and polysaccharides). They all tend to occur as very small particles (1-1,000 nm in diameter). Most natural amorphous particles are unstable and tend to transform with time towards more crystalline forms, either by aging or possibly, by dissolution and re-crystallization. Such transformations affect the fate of sorbed micropollutants and the scavenging properties are therefore changed. As these entities are sensitive to dehydration (aggregation, changes in the morphology), it is highly important to observe their morphology in their natural environment and understand their composition at the scale of the individual particles. Also for the understanding and optimization of water treatment technologies, the knowledge of the occurrence and behavior of nano-particles is of high importance. Some of the possible particle analysis methods are presented: aggregation processes, biomineralization, bacterial adhesion, biofilms in freshwaters, ferrihydrite as heavy metals remover from storm water. These examples demonstrate the capabilities and focus of the microscopes. Atomic Force Microscopy (AFM) allows to analyze the particles in their own environment, meaning in air or in the water. Thus, native aspects of particles can be observed. As well, forces of interactions between particles or between particles and other surfaces such as membranes will be highly valuable data. ScanningElectron Microscopy (SEM) and for higher lateral resolution, Transmission Electron Microscopy (TEM) allow measurement of the morphology and composition. Especially, TEM coupled with Electron Energy Loss Spectroscopy (TEM-EELS) is a powerful technique for elemental analysis

Cryo-fixed yeast Paramecia and sea urchin embryos were investigated with an in-lens type field-emission SEM using a cold stage. The goal was to further develop and investigate the processing of frozen samples for the low-temperature scanningelectron microscope (LTSEM). Uncoated frozen-hydrated samples were imaged with the low-voltage backscattered electron signal (BSE). Resolution and contrast were sufficient to visualize cross-fractured membranes, nuclear pores and small vesicles in the cytoplasm. It is assumed that the resolution of this approach is limited by the extraction depth of the BSE which depends upon the accelerating voltage of the primary beam (V0). In this study, the lowest possible V0 was 2.6 kV because below this value the sensitivity of the BSE detector is insufficient. It is concluded that the resolution of the uncoated specimen could be improved if equipment were available for high-resolution BSE imaging at 0.5-2 kV. Higher resolution was obtained with platinum cryo-coated samples, on which intramembranous particles were easily imaged. These images even show the ring-like appearance of the hexagonally arranged intramembranous particles known from high-resolution replica studies. On fully hydrated samples at high magnification, the observation time for a particular area is limited by mass loss caused by electron irradiation. Other potential sources of artefacts are the deposition of water vapour contamination and shrinkage caused by the sublimation of ice. Imaging of partially dehydrated (partially freeze-dried) samples, e.g. high-pressure frozen Paramecium and sea urchin embryos, will probably become the main application in cell biology. In spite of possible shrinkage problems, this approach has a number of advantages compared with any other electron microscopy preparation method: no chemical fixation is necessary, eliminating this source of artefacts; due to partial removal of the water additional structures in the cytoplasm can be investigated

GaN nanotubes with coaxial InGaN quantum wells were analyzed by scanning transmission electron microscopy in order to determine their structural properties as well as the indium distribution across the InGaN quantum wells. For the latter, two process steps are necessary. First, a technique to prepare cross-sectional slices out of the nanotubes has been developed. Second, an existing scanning transmission electron microscopy analysis technique has been extended with respect to the special crystallographic orientation of this type of specimen. In particular, the shape of the nanotubes, their defect structure, and the incorporation of indium on different facets were investigated. The quantum wells preferentially grow on m-planes of the dodecagonally shaped nanotubes and on semipolar top facets while no significant indium signal was found on a-planes. An averaged indium concentration of 6% to 7% was found by scanning transmission electron microscopy analysis and could be confirmed by cathodoluminescence measurements.

To better understand the nature of particulates in low-Earth orbit (LEO), and their effects on spacecraft hardware, we are analyzing residues found in impacts on the Long Duration Exposure Facility (LDEF) tray clamps. LDEF experiment trays were held in place by 6 to 8 chromic-anodized aluminum (6061-T6) clamps that were fastened to the spacecraft frame using three stainless steel hex bolts. Each clamp exposed an area of approximately 58 sq cm (4.8 cm x 12.7 cm x .45 cm, minus the bolt coverage). Some 337 out of 774 LDEF tray clamps were archived at JSC and are available through the Meteoroid & Debris Special Investigation Group (M&D SIG). Optical scanning of clamps, starting with Bay/Row A01 and working toward H25, is being conducted at JSC to locate and document impacts as small as 40 microns. These impacts are then inspected by ScanningElectron Microscopy/Energy Dispersive X-ray Analysis (SEM/EDXA) to select those features which contain appreciable impact residue material. Based upon the composition of projectile remnants, and using criteria developed at JSC, we have made a preliminary discrimination between micrometeoroid and space debris residue-containing impact features. Presently, 13 impacts containing significant amounts of unmelted and semi-melted micrometeoritic residues were forwarded to Centre National d'Etudes Spatiales (CNES) in France. At the CNES facilities, the upgraded impacts were analyzed using a JEOL T330A SEM equipped with a NORAN Instruments, Voyager X-ray Analyzer. All residues were quantitatively characterized by composition (including oxygen and carbon) to help understand interplanetary dust as possibly being derived from comets and asteroids.

Decellularized tissues have been used to investigate the extracellular matrix (ECM) in a number of different tissues and species. Santi and Johnson JARO 14:3-15 (2013) first described the decellularized inner ear in the mouse, rat, and human using scanning thin-sheet laser imaging microscopy (sTSLIM). The purpose of the present investigation is to examine decellularized cochleas in the mouse and human at higher resolution using scanningelectron microscopy (SEM). Fresh cochleas were harvested and decellularized using detergent extraction methods. Following decellularization, the ECM of the bone, basilar membrane, spiral limbus, and ligament remained, and all of the cells were removed from the cochlea. A number of similarities and differences in the ECM of the mouse and human were observed. A novel, spirally directed structure was present on the basilar membrane and is located at the border between Hensen and Boettcher cells. These septa-like structures formed a single row in the mouse and multiple rows in the human. The basal lamina of the stria vascularis capillaries was present and appeared thicker in the human compared with the mouse. In the mouse, numerous openings beneath the spiral prominence that previously housed the root processes of the external sulcus cells were observed but in the human there was only a single row of openings. These and other anatomical differences in the ECM between the mouse and human may reflect functional differences and/or be due to aging; however, decellularized cochleas provide a new way to examine the cochlear ECM and reveal new observations. PMID:27029011

Z{sub eff}, a parameter representing an 'effective atomic number' for a material, plays an important role in the Electronic Baggage Scanning Program (EBSP) to detect threats in dual-energy computed tomography (CT) baggage-scanning systems. We believe that Z{sub eff}, as defined and used on this program, does not provide the accurate representation of a material's x-ray absorption properties that is needed by the EBSP. We present the case for a new method that defines an effective atomic number for compounds and mixtures, which we refer to as Z{sub e}. Unlike Z{sub eff}, Z{sub e} is tied by definition to the x-ray absorption properties of each specific material. Use of this alternative will provide a more accurate scale for calibrating Micro-CT and EDS systems against standard reference materials and will provide a more accurate physical characterization of the x-ray properties of materials evaluated on those systems. This document: (1) Describes the current usage of the Z{sub eff} parameter; (2) Details problems entailed in the use of the Z{sub eff} parameter; (3) Proposes a well-defined alternative - Z{sub e}; (4) Proposes and demonstrates an algorithm for optimally associating Z{sub e} with any specified compound or mixture; (5) Discusses issues that can impact the usefulness of an effective-Z model; and (6) Recommends that, in order that the chosen effective-Z parameter not materially impact the accuracy of data produced by the EBSP program, the use of Z{sub eff} be replaced by Z{sub e}.

Species of Cruzia are parasites of the large intestine of marsupials, reptiles, amphibians, and mammalians. Cruzia tentaculata specimens were collected from the large intestine of Didelphis marsupialis (Mammalia: Didelphidae) from Colombia (new geographical record) and from Brazil and analyzed by light and scanningelectron microscopy. The morphology of males and females by light microscopy corroborated most of the previous description and the ultrastructure by scanningelectron microscopy evidence: the topography of the cuticle, deirids, amphids, phasmids in both sexes, a pair of papillae near the vulva opening, and the number and location of male caudal papillae, adding new features for species identification only observed by this technique. PMID:19130086

Several plant preparations are administered for treatment of stone disease without scientific basis. This paper presents the results of in vitro and animal experimental studies using scanningelectron microscopy (SEM) in the identification of the therapeutic properties of trial drugs in medicine. In the first set of the study, urinary crystals namely calcium oxalate monohydrate and calcium oxalate dehydrate were grown in six sets of Hane's tubes in silica gel medium. Trial drugs namely scoparia dulcis Lynn, musa sapiens and dolicos biflorus were incorporated in the gel medium to identify the dopant effect of the trial drugs on the size and extent of crystal column growth. The changes in morphology of crystals were studied using SEM. In the second set, six male Wistar rats each were calculogenised by administering sodium oxalate and ethylene glycol and diabetised using streptozotocin. The SEM changes of calculogenisation were studied. The rats were administered trial drugs before calculogenisation or after. The kidneys of the rats studied under the scanningelectron microscope showed changes in tissue morphology and crystal deposition produced by calculogenisation and alterations produced by addition of trial drugs. The trial drugs produced changes in the pattern of crystal growth and in the crystal morphology of both calcium oxalate monohydrate and calcium oxalate dihydrate grown in vitro. Elemental distribution analysis showed that the crystal purity was not altered by the trial drugs. Scoparia dulcis Lynn was found to be the most effective anticalculogenic agent. Musa sapiens and dolicos biflorus were found to have no significant effect in inhibiting crystal growth. The kidneys of rats on calculogenisation showed different grades of crystals in the glomerulus and interstitial tissues, extrusion of the crystals into the tubular lumen, collodisation and tissue inflammatory cell infiltration. Scoparia dulcis Lynn exhibited maximum protector effect against the

The authors report on the generation of localized defects on single-walled carbon nanotubes by means of a hydrogen electron cyclotron resonance plasma. The defects have been investigated using scanning tunneling microscopy (STM) and show an apparent topographic height in the STM of 1-3 A. In the vicinity of defects, characteristic superstructures could be observed and the patterns could be simulated using a simple model based on large momentum scattering of the valence electrons. The combination of low structural damage and high electronic activity opens the possibility to tune the electronic transport properties using such defects.

We clarify the scanningelectron microscopic contrast mechanism for imaging a buried SiO(2) trench microstructure with interface trapped charges by simulating both electron scattering and transport. Here, the interface trapped charges make the SiO(2) film more negatively charged and increase excess holes in the space charge distribution of the electron scattering region. The generated positive surface electric field thus redistributes some emitted secondary electrons and results in the dark contrast. This contrast mechanism is validated by comparing with experiments, and it may also provide an interesting approach for imaging and detecting deep interface trapped charges in insulating films. PMID:19029106

In contrast to advancements in the fabrication of new superhydrophobic materials, the characterization of their water repellency and quality is often coarse and unsatisfactory. In view of the problems and inaccuracies, particularly in the measurement of very high contact angles, we developed alternative methods for the characterization of superhydrophobic surfaces. It was found that adhering water remnants after immersion are a useful criterion in determining the repellency quality. In this study, we introduce microscopy methods to detect traces of water-resembling test liquids on superhydrophobic surfaces by scanningelectron microscopy (SEM) or fluorescence light microscopy (FLM). Diverse plant surfaces and some artificial superhydrophobic samples were examined. Instead of pure water, we used aqueous solutions containing a detectable stain and glycerol in order to prevent immediate evaporation of the microdroplets. For the SEM examinations, aqueous solutions of lead acetate were used, which could be detected in a frozen state at -90 °C with high sensitivity using a backscattered electron detector. For fluorescence microscopy, aqueous solutions of auramine were used. On different species of superhydrophobic plants, varying patterns of remaining microdroplets were found on their leaves. On some species, drop remnants occurred only on surface defects such as damaged epicuticular waxes. On others, microdroplets regularly decorated the locations of increased adhesion, particularly on hierarchically structured surfaces. Furthermore, it is demonstrated that the method is suitable for testing the limits of repellency under harsh conditions, such as drop impact or long-enduring contact. The supplementation of the visualization method by the measurement of the pull-off force between a water drop and the sample allowed us to determine the adhesive properties of superhydrophobic surfaces quantitatively. The results were in good agreement with former studies of the water

Plasma etching and ashing for demonstrating the three-dimensional ultrastructure of the internal organs of helminths is described. Adult worms of the cestode Caryophyllaeides fennica were dehydrated through an ethanol series, critical point dried (Polaron E3000) and sputter coated with 60% gold-palladium (Polaron E5100) and glued to a standard scanningelectron microscope (SEM) stub positioned as required for ashing. After initial SEM viewing of worm surfaces for orientation, stubs were placed individually in the reactor chamber of a PT7150 plasma etching and ashing machine. Worms were exposed to a radio frequency (RF) potential in a low pressure (0.2 mbar) oxygen atmosphere at room temperature. The oxidation process was controlled by varying the times of exposure to the RF potential between 2 to 30 min, depending on the depth of surface tissue to be removed to expose target organs or tissues. After each exposure the oxidized layer was blown from the surface with compressed air, the specimen sputter-coated, and viewed by SEM. The procedure was repeated as necessary, to progressively expose successive layers. Fine details of organs, cells within, and cell contents were revealed. Ashing has the advantage of providing three dimensional images of the arrangement of organs that are impossible to visualize by any other procedure, for example facilitating testes counts in cestodes. Both freshly-fixed and long-term stored helminths can be ashed. Ashing times to obtain the desired results were determined by trial so that some duplicate material was needed. PMID:16469178

The fine structural features and regional differences of the ependyma in adult pigeons have been investigated by scanningelectron microscopy. Pigeons of either sex were fixed with buffered glutaraldehyde (3%) and formaldehyde (0.5%) by intravascular perfusion. The brain was dissected using section planes adequate to expose each part of the ventricular system. The specimens were then dehydrated, critical point dried and sputtered with gold. Depending upon the distribution of cilia, microvilli and single cilia, different areas were recognised in the 4 ventricles. The topographic locations of these areas were determined using the atlas of Karten & Hodos (1967). The medial surfaces of the 1st and 2nd lateral ventricles are more densely ciliated than the lateral surfaces. In the floor of the 4th ventricle the medial part is less ciliated than the lateral parts. The circumventricular organs (subseptal organ, organum vasculosum of the lamina terminalis, infundibulum, choroid plexus, subcommissural organ, area postrema) show very characteristic surfaces and are surrounded by a transitional zone with the nonspecialized ependyma. In contrast, in the paraventricular organ the transition to the nonspecialized ependyma is rather abrupt. The ependyma covering the trochlear nucleus appears densely ciliated, differing from that of the classic circumventricular organs. Finally, the existence of openings in the caudal medullary velum, which represent direct communications between the ventricles and the subarachnoid space, was demonstrated. Images Fig. 2 Fig. 3 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 PMID:8157492

The dry weight of tendon tissue is accounted for mainly by collagen fibers. Accordingly, the tendon-healing process primarily involves repair of collagen fibers. During the remodeling phase of tendon healing, newly proliferating collagen fibers are transformed into a mature repaired tendon. Despite the importance of this phenomenon, the details of fibrous rebuilding have not been reported previously. The aim of this study was to visualize the ultrastructural changes and to obtain a clear understanding of the reorganization of the collagen fibers in the tendon repair site, using rat Achilles tendons. We used scanningelectron microscopy (SEM) with cell maceration as the main method of analysis. Pretreatment with cell maceration removed the cellular components successfully. This allowed precise visualization of each collagen fiber and the three-dimensional network of the fibers. This study was the first to apply the cell-maceration/SEM method to observe tendon tissue. Seven days after surgery, new collagen fibers grew extensively in the repair site in a random arrangement. Fourteen days after surgery, the collagen fibers began to form an axial arrangement. Near the tendon stump, this change progressed from the outer layer to the core region. On the other hand, in the middle of the repair site, it progressed from the core to the outer layer. Change in the axial arrangement of collagen fibers contributes to the connection between the repair site and the tendon stump and to the separation of the repair site from the paratenon. PMID:22859848

The mammalian tongue has evolved for specialized functions in different species. The structure of its papillae tells about the animal's diet, habit, and taxonomy. The opossum has four kinds of lingual papillae (filiform, conical, fungiform, vallate). Scanningelectron microscopy of the external features, connective tissue cores, and corrosion casts of the microvasculature show the filiform papillae have a spearhead-like main process and spiny accessory processes around the apical part of the main process. The shape and number of both processes depend on their position on the tongue. On the apex, the main processes have shovel-like capillary networks and the accessory processes have small conical networks. On the lingual radix, the processes have small capillary loops. In the patch region, conical papillae have capillaries arranged as a full sail curving posteriorly. The fungiform papillae are scattered among the filiform papillae and have capillary baskets beneath each taste bud. Giant fungiform papillae on the tongue tip are three to four times larger than the ones on the lingual body. Capillaries of giant papillae form a fan-shaped network. The opossum has three vallate papillae arranged in a triangle. Their tops have secondary capillary loops but not their lateral surfaces. Mucosal folds on the posterolateral border have irregular, fingerlike projections with cylindrical capillary networks. These findings and the structure of the rest of the masticatory apparatus suggest the lingual papillae of opossum have kept their ancestral carnivorous features but also developed the herbivore characteristics of other marsupials. PMID:16079016

It is a well-known fact that scanningelectron microscopic (SEM) image acquisition is mainly affected by nonlinearities and instabilities of the column and probe-specimen interaction; in turn, producing a shift in the image points with respect to many parameters and time, in particular. Even though this drift is comparatively less in modern SEMs, it is still an important factor to consider in most of the SEM-based applications. In this airticle, a simple and real-time method is proposed to estimate the global drift from a set of target images using image phase correlation, and to model its evolution by using the recursive equations of time and magnification. Based on the developed model, it is opted to use a Kalman filter in real time for accurate estimation and removal of the drift from the images. The developed method is tested using the images from a tungsten filament gun SEM (Jeol JSM 820) and a field effect gun SEM (FEI Quanta 200). The derived results show the effectiveness of the developed algorithm and also demonstrates its ability to be used in robotics as well as in material characterization under SEM.

The morphological study of the Odontocete organ of Corti, together with possible alterations associated with damage from sound exposure, represents a key conservation approach to assess the effects of acoustic pollution on marine ecosystems. By collaborating with stranding networks from several European countries, 150 ears from 13 species of Odontocetes were collected and analyzed by scanning (SEM) and transmission (TEM) electron microscopy. Based on our analyses, we first describe and compare Odontocete cochlear structures and then propose a diagnostic method to identify inner ear alterations in stranded individuals. The two species analyzed by TEM (Phocoena phocoena and Stenella coeruleoalba) showed morphological characteristics in the lower basal turn of high-frequency hearing species. Among other striking features, outer hair cell bodies were extremely small and were strongly attached to Deiters cells. Such morphological characteristics, shared with horseshoe bats, suggest that there has been convergent evolution of sound reception mechanisms among echolocating species. Despite possible autolytic artifacts due to technical and experimental constraints, the SEM analysis allowed us to detect the presence of scarring processes resulting from the disappearance of outer hair cells from the epithelium. In addition, in contrast to the rapid decomposition process of the sensory epithelium after death (especially of the inner hair cells), the tectorial membrane appeared to be more resistant to postmortem autolysis effects. Analysis of the stereocilia imprint pattern at the undersurface of the tectorial membrane may provide a way to detect possible ultrastructural alterations of the hair cell stereocilia by mirroring them on the tectorial membrane. PMID:25269663

The brownmillerite phase A2B2O5 consists of ordered oxygen vacancies in alternate perovskite layers forming chiral tetrahedral chains. The handedness of these tetrahedral chains control the polarization of the structure. The current study focuses on 1-1 brownmillerite superlattices grown on a SrTiO3 substrates using molecular beam epitaxy. The B-site in this structure is iron throughout the superlattice film, while the A-site alternates between calcium and strontium in the superlattice layers. In this study, we use atomic resolution aberration corrected scanning transmission electron microscopy (STEM) to investigate the structure and chemistry of the film-substrate interface as well as the chemical structure of the superlattice. Atom positions are determined to measure displacement vectors of A-site cations in the superlattice structure. D.M., G.A.S., V.G. and N.A. were supported by the National Science Foundation under Grant No. DMR-1420620. E.J.M. and S.J.M. were supported by the National Science Foundation under Grant No. DMR-1151649.

Spectroscopic and morphological studies, designed to improve our understanding of the physicochemical phenomena that occur during zircon crystallization, are presented. The zircon fission track method (ZFTM) is used routinely in various laboratories around the world; however, there are some methodological difficulties needing attention. Depending on the surface fission track density observed under an optical microscope, the zircon grain surfaces are classified as homogeneous, heterogeneous, hybrid, or anomalous. In this study, zircon grain surfaces are characterized using complementary techniques such as optical microscopy (OM), micro-Raman spectroscopy, and scanningelectron microscopy (SEM), both before and after chemical etching. Our results suggest that anomalous grains have subfamilies and that etching anisotropy related to heterogeneous grains is due to different crystallographic faces within the same polished surface that cannot be observed under an optical microscope. The improved methodology was used to determine the zircon fission track ages of samples collected from the Bauru Group located in the north of Paraná Basin, Brazil. A total of 514 zircon grains were analyzed, consisting of 10% homogeneous, about 10% heterogeneous, about 20% hybrid, and 60% anomalous grains. These results show that the age distributions obtained for homogeneous, heterogeneous, and hybrid grains are both statistically and geologically compatible. PMID:25014598

Submicronic fungal fragments have been observed in in vitro aerosolization experiments. The occurrence of these particles has therefore been suggested to contribute to respiratory health problems observed in mold-contaminated indoor environments. However, the role of submicronic fragments in exacerbating adverse health effects has remained unclear due to limitations associated with detection methods. In the present study, we report the development of an indirect immunodetection assay that utilizes chicken polyclonal antibodies developed against spores from Aspergillus versicolor and high-resolution field emission scanningelectron microscopy (FESEM). Immunolabeling was performed with A. versicolor fragments immobilized and fixed onto poly-l-lysine-coated polycarbonate filters. Ninety percent of submicronic fragments and 1- to 2-μm fragments, compared to 100% of >2-μm fragments generated from pure freeze-dried mycelial fragments of A. versicolor, were positively labeled. In proof-of-concept experiments, air samples collected from moldy indoor environments were evaluated using the immunolabeling technique. Our results indicated that 13% of the total collected particles were derived from fungi. This fraction comprises 79% of the fragments that were detected by immunolabeling and 21% of the spore particles that were morphologically identified. The methods reported in this study enable the enumeration of fungal particles, including submicronic fragments, in a complex heterogeneous environmental sample. PMID:26092450

The present light microscopy (LM) and scanningelectron microscopy (SEM) studies on porcine gallbladder mucosa provide a description of the microstructures of great functional importance such as mucosal folds, the epithelium, glands, and lymphatic nodules. The results showed the regional structural differences of the porcine gallbladder wall. Depending on the part of the gallbladder, three types of mucosal structures were described: simple and branched folds and mucosal crypts. An important structural feature found in the mucosa is connected with the structural variety of type of mucosal folds, which change from simple located in the neck, to most composed, i.e., branched or joined, in the polygonal crypts toward the fundus of the gallbladder. The morphometric analysis showed statistically significantly differences in the form and size of the folds and between the fundus, body, and neck of the gallbladder. Differences in the size of mucosal epithelium are discussed in terms of processes of synthesis and secretion of glycoproteins. Regional, species-specific differences in morphology of mucosal subepithelial glands, i.e., their secretory units and openings, and intensity of mucus secretion were described. Our results on the pig gallbladder show adaptation and/or specialization in particular areas of the mucosa for (1) secretion of mucus in the neck or body of gallbladder and (2) for cyclic volume changes, especially in the fundus of gallbladder. The description of the microstructures of mucosa in the porcine gallbladder could be useful as reference data for numerous experiments on the bile tract in the pig. PMID:25604381

This work highlights the importance of in situ experiments for an improved understanding of graphene growth on copper via metal-catalyzed chemical vapor deposition (CVD). Graphene growth inside the chamber of a modified environmental scanningelectron microscope under relevant low-pressure CVD conditions allows visualizing structural dynamics of the active catalyst simultaneously with graphene nucleation and growth in an unparalleled way. It enables the observation of a complete CVD process from substrate annealing through graphene nucleation and growth and, finally, substrate cooling in real time and nanometer-scale resolution without the need of sample transfer. A strong dependence of surface dynamics such as sublimation and surface premelting on grain orientation is demonstrated, and the influence of substrate dynamics on graphene nucleation and growth is presented. Insights on the growth mechanism are provided by a simultaneous observation of the growth front propagation and nucleation rate. Furthermore, the role of trace amounts of oxygen during growth is discussed and related to graphene-induced surface reconstructions during cooling. Above all, this work demonstrates the potential of the method for in situ studies of surface dynamics on active metal catalysts. PMID:25584770

Scanningelectron microscopy (SEM) and energy dispersive spectrometry (EDS) have been used for in situ analysis of minerals in peats by combining methods for producing oriented microtome sections of peat with methods for critical point drying. The combined technique allows SEM analysis of the inorganic components and their associated botanical constituents, along with petrographic identification of the botanical constituents. In peat deposits with abundant fluvial- or marine-derived minerals, one may use the above technique and/or medium- or low-temperature ashing followed by x-ray diffraction to readily identify the various mineral components. However, in some freshwater environments the scarcity of non-silica minerals makes the above techniques impractical. By separating the inorganic residues from the peat, one can isolate the non-silica mineral matter in the SEM for analysis by EDS. Furthermore, such separation allows SEM analysis of features and textures of both silica and non-silica mineral particles that might otherwise be unidentifiable. Results indicate the occurrence of detritial minerals in both Okefenokee and Snuggedy Swamp peats, the presence of authigenic or diagenetic minerals growing within peats, and dissolution features on freshwater sponge spicules that may account for the absence of spicules in Tertiary lignites.

An atmospheric scanningelectron microscope (ASEM) with an open sample chamber and optical microscope (OM) is described and recent developments are reported. In this ClairScope system, the base of the open sample dish is sealed to the top of the inverted SEM column, allowing the liquid-immersed sample to be observed by OM from above and by SEM from below. The optical axes of the two microscopes are aligned, ensuring that the same sample areas are imaged to realize quasi-simultaneous correlative microscopy in solution. For example, the cathodoluminescence of ZnO particles was directly demonstrated. The improved system has (i) a fully motorized sample stage, (ii) a column protection system in the case of accidental window breakage, and (iii) an OM/SEM operation system controlled by a graphical user interface. The open sample chamber allows the external administration of reagents during sample observation. We monitored the influence of added NaCl on the random motion of silica particles in liquid. Further, using fluorescence as a transfection marker, the effect of small interfering RNA-mediated knockdown of endogenous Varp on Tyrp1 trafficking in melanocytes was examined. A temperature-regulated titanium ASEM dish allowed the dynamic observation of colloidal silver nanoparticles as they were heated to 240°C and sintered. PMID:25062041

Aberration-corrected scanning transmission electron microscopes (STEMs) provide sub-Angstrom lateral resolution; however, the large convergence angle greatly reduces the depth of field. For microscopes with a small depth of field, information outside of the focal plane quickly becomes blurred and less defined. It may not be possible to image some samples entirely in focus. Extended depth-of-field techniques, however, allow a single image, with all areas in focus, to be extracted from a series of images focused at a range of depths. In recent years, a variety of algorithmic approaches have been employed for bright-field optical microscopy. Here, we demonstrate that some established optical microscopy methods can also be applied to extend the ~6 nm depth of focus of a 100 kV 5th-order aberration-corrected STEM (α{sub max} = 33 mrad) to image Pt-Co nanoparticles on a thick vulcanized carbon support. These techniques allow us to automatically obtain a single image with all the particles in focus as well as a complimentary topography map.

For nearly 50 years, investigators using light microscopy have vaguely alluded to a unique type of snow crystal that has become known as an irregular snow crystal. However, the limited resolution and depth-of-field of the light microscope has prevented investigators from characterizing these crystals. In this study, a field-emission scanningelectron microscope, equipped with a cold stage, was used to document the structural features, physical associations, and atmospheric metamorphosis of irregular snow crystals. The crystals appear as irregular hexagons, measuring 60 to 90 mm across, when viewed from the a-axis. Their length (c-axis) rarely exceeds the diameter. The irregular crystals are occasionally found as secondary particles on other larger forms of snow crystals; however, they most frequently occur in aggregates consisting of more than 100 irregular crystals. In the aggregates, the irregular crystals have their axes oriented parallel to one another and, collectively, tend to form columnar structures. Occasionally, these columnar structures exhibit rounded faces along one side, suggesting atmospheric metamorphoses during formation and descent. In extreme cases of metamorphoses, the aggregates would be difficult to distinguish from graupel. Frost, consisting of irregular crystals, has also been encountered, suggesting that atmospheric conditions that favor their growth can also occur terrestrially. PMID:12392356

Pregnant CBA/CBA mice were exposed to 0.5, 1 and 2 Grey (Gy), (1 Gy = 100 rad) in single doses with whole body gamma-irradiation on the 12th, 13th and 16th gestational days, respectively. The animals were tested at an age of one month for vestibular and cochlear function. Thereafter the inner ears were analyzed with scanningelectron microscopy. A morphological analysis with cytocochleograms was performed. Morphological changes in the vestibular part showed gross malformations in the cristae ampullares. Hair cells of type I seemed to be more severely changed than hair cells type II. The macula utriculi also showed malformations of the otoconia. All these changes were more pronounced when the irradiation was given early during pregnancy and with the highest doses used, except the otoconia which were more injured when irradiated day 16 of gestation. No disturbances of the equilibrium reflexes were noted. In the cochlea a dose-dependent, time-related damage pattern was demonstrated with pathological changes of outer (OHC) and inner (IHC) hair cells. When tested electrophysiologically for auditory function with auditory brainstem recordings (ABR), elevated thresholds were revealed different in shape depending on when during pregnancy irradiation took place. A good correlation existed between the morphological changes as seen in the cytocochleograms and the functional changes documented with the ABR.

Leachate sludge samples were taken from two municipal solid waste sites of Jelekong and Sarimukti in Bandung, Indonesia. Their magnetic mineralogy and granulometry were analyzed to discriminate the sources of magnetic minerals using X-ray diffraction (XRD), scanningelectron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM-EDX) and rock magnetism. SEM-EDX analyses infer that the main magnetic minerals in the leachate sludge are iron oxides. In terms of their morphology, the grains from Jelekong are mostly octahedral and angular, which are similar to the general shapes of magnetic grains from the local soils. The grains from Sarimukti, on the other hand, are dominated by imperfect spherule shapes suggesting the product of combustion processes. Hysteresis parameters verify that the predominant magnetic mineral in leachate sludge is low coercivity ferrimagnetic mineral such as magnetite (Fe(3)O(4)). Furthermore, comparisons of rock magnetic parameters show that the magnetic minerals of soil samples from Jelekong have higher degree of magnetic pedogenesis indicating higher proportion of superparamagnetic/ultrafine particles than those of soil samples from Sarimukti. The plot of susceptibilities ratio versus coercive force has a great potential to be used as a discriminating tool for determining the source of magnetic minerals. PMID:20395044

Background: Comparison of the demineralization potential of four luting cements, i.e. zinc phosphate, conventional glass ionomer cement (GIC), resin-modified GIC and acid modified composite resin. Materials and Methods: This study was conducted on 75 extracted premolar teeth, which were grouped into five, each group containing 15 teeth. Groups were non-banded control, teeth cemented with the above-mentioned cements. These were incubated at 37°C for 30 days in sealable plastic containers, after which the teeth were debanded, cleaned and placed in acid gelatin solution at 37°C for 4 weeks to simulate the cariogenic solution. Then, the teeth were sectioned and examined under scanningelectron microscope. The depth of the carious lesions was measured using image analysis with Digimizer software. Results: The depth of the carious lesions was maximum with non-banded group, followed by zinc phosphate, acid modified composite resin, resin-modified GIC and conventional GIC. Conclusions: Among the four orthodontic banding cements compared, the enamel demineralization potential is least with conventional GIC, followed by resin-modified GIC, acid modified composite resin and zinc phosphate. PMID:25859103

This study was undertaken to determine the prevalence of anoplocephalid cestodes in sheep and goats in Senegal. Intestines of 462 sheep and 48 goats were examined; 47.4% of sheep and 6.2% of goats were infected. The species identified and their prevalence were, among sheep, Avitellina centripunctata 38.7%, Moniezia expansa 15.4%, Stilesia globipunctata 16.7%, and Thysaniezia ovilla 0.4%. Among goats, they were M. expansa 6.2% and T. ovilla 2.1%. The prevalence of all species was not statistically different between dry and rainy seasons. The infections were single or multiple. Indeed, 56.2% of sheep were infected by a single species, 37.4% by two species, and 6.4% by three species. For goats, 66.7% were infected by M. expansa and 33.3% by both M. expansa and T. ovilla. Scanningelectron microscopic (SEM) observations of tapeworms show the general diagnosis characters of these species. PMID:27597893

The use of the ScanningElectron Microscope has made it possible through observation to study the human cervical mucus through the various stages of the ovarian cycle, as well as to describe the significant variations of the meshed woof making up the ultrastructure during the ovarian cycle. While the slackening of the woof and the dimension of the meshes are minimal at both the beginning and end of the cycle, they reach a maximum on forteenth day. In the ovulatory period, lateral expansions from the filaments are numerous. On the other hand, median and terminal thicknesses are almost inexistant during the same period : their frequency decreases during the first part of the cycle, then increases during the luteal phase. During both the preceding and following days of ovulation, one can observe numerous twistings at the level of the filaments which probably express the relaxation and then contraction of the latter. The preparatory technique as well as the method of observation used appear reliable enough to allow a comparison of the cervical mucus ultrastructure in varied physiological, pathological and experimental situations. PMID:956619

Introduction: Presence of surface defects in endodontic instruments can lead to unwanted complications such as instrument fracture and incomplete preparation of the canal. The current study was conducted to evaluate the effect of autoclave cycles on surface characteristics of S-File by scanningelectron microscopy (SEM). Methods and Materials: In this experimental study, 17 brand new S-Files (#30) were used. The surface characteristics of the files were examined in four steps (without autoclave, 1 autoclave cycle, 5 autoclave cycles and 10 autoclave cycles) by SEM under 200× and 1000× magnifications. Data were analyzed using the SPSS software and the paired sample t-test, independent sample t-test and multifactorial repeated measures ANOVA. The level of significance was set at 0.05. Results: New files had debris and pitting on their surfaces. When the autoclave cycles were increased, the mean of surface roughness also increased at both magnifications (P<0.05). Moreover, under 1000× magnification the multifactorial repeated measures ANOVA showed more surface roughness (P<0.001). Conclusion: Sterilization by autoclave increased the surface roughness of the files and this had was directly related to the number of autoclave cycles. PMID:26843874

The longicorn beetle Xylotrechus grayii (White, 1855) has been spreading rapidly in China, causing mass mortality of honeysuckle which is economically and medicinally important. In order to elucidate the mechanisms of mate and host location and to advance efficient control methods, antennal sensilla features were investigated in both sexes of X. grayii using scanningelectron microscopy (SEM). The filiform antennae of both sexes consist of scape, pedicel, and nine flagellomeres (f1-9). Five types of sensilla were observed: sensilla chaetica (5 subtypes, SC1-5), sensilla basiconica (4 subtypes, SB1-4), Böhm bristles (Bm), grooved peg sensilla (Gp), and sensilla campaniformia (Ca). SC were most common on the antennae, followed by SB and Bm. No significant sexual differences in the type, amounts, and distribution of antennal sensilla were found except for the distribution of SB clusters and Ca. SB clusters and Ca occurred on f1-8 of male antennae but were absent on those segments in females, suggesting a potential function as receptors for female sex pheromones. The putative functions of other sensilla are discussed based on their characteristics in related species. This study provides an important foundation for further research on sensory mechanisms and control measures of X. grayii. PMID:24458796

Triangular parallel-plate nanocapacitors were fabricated by a combination of microsphere lithography and physical vapor deposition. The devices were comprised of a 20 nm layer of dielectric material sandwiched between two 20 nm layers of gold. Dielectric materials with a range of relative permittivities were investigated. Charging of the capacitors was probed in a scanningelectron microscope (SEM) by monitoring the change in brightness of the images of the devices as a function of time. The time constants, RC, associated with the charging of the capacitors, were extracted from the SEM grayscale data. The resulting average RC values were 248 ± 27 s for SiO2, 70 ± 8 s for Al2O3, 113 ± 80 s for ZnO and 125 ± 13 s for HfO2. These values are consistent with the anticipated RC values based on the resistivities and permittivities of the materials used in the devices and importantly, were measured without the need to attach any wires or leads.

A low-energy Nd:YAG laser was used to irradiate extracted human teeth coated with a black energy-absorbent laser initiator in a study to determine the extent of the morphologic changes produced in the enamel surface. The laser initiator was applied to a cleaned enamel surface and irradiated at an energy output of 30 mJ or 75 mJ. Both energy levels produced morphologic changes of the surface. There was a sharp line of demarcation between the coated, irradiated area and the surrounding noncoated enamel surface. The scanningelectron microscope view at the lower energy level showed that the surface had melted and reformed with numerous small, bubble-like inclusions. The 75 mJ energy level showed individual impact craters with shallow centers and raised edges containing numerous pores and large, bubble-like inclusions. Etching is a dental procedure in which an acid is normally used to remove a thin outer layer of the tooth structure. This is necessary to create a roughened, irregular surface in order to provide mechanical retention for dental restorative materials. The changes produced by the laser in this study suggest a simple, effective, and controlled method of etching the enamel surface of a tooth by altering its surface characteristics.

Scanningelectron microscopy (SEM) has occasionally been used by anthropologists and forensic scientists to look at morphological characteristics that certain implements leave on bone. However, few studies have addressed techniques or protocols for assessing quantitative differences between tool marks on bone made by different bladed implements. In this study, the statistical variation in cut mark width was examined between control and test samples on bone using a scalpel blade, paring knife, and kitchen utility knife. Statistically significant differences (p < .0005) were found between cut marks made by the same knife under control and test conditions for all three knife types used in the study. When the control sample and test samples were examined individually for differences in mean variation between knife types, significant differences were also found (p < .0005). While significant differences in cut mark width were found, caution should be used in trying to classify individual cut marks as being inflicted by a particular implement, due to the overlap in cut mark width that exists between different knife types. When combined, both quantitative and qualitative analyses of cut marks should prove to be more useful in trying to identify a suspect weapon. Furthermore, the application of SEM can be particularly useful for assessing many of these features. PMID:11714137

Particulate materials with unique functional properties have been the focus of much attention in recent years. Of particular interest, due to their considerable scientific and technological importance, are particles coated with nanoparticles. These have greatly stimulated interest for their novel structure and properties. In these kinds of particulate materials, the interface structures between the support particle and the nanoparticle play a crucial role in controlling their properties. Consequently, imaging of the atomic structures at the interfaces can provide deep understanding of the relationship between the particulate and the corresponding properties. Z-contrast scanning transmission electron microscope (STEM) provides a new view of materials on the atomic scale, a direct image of atomic structure composition which can be interpreted without the need for any preconceived model structure. Therefore it is a powerful tool in the study of particulate materials. In this report, the authors present the structures of 18 micron diameter alumina particles coated with Ag nanoparticles. Particulates were prepared by a laser ablation technique, which involves laser ablation of the target material (Ag) onto a fluidized bed of core particles (alumina). The core alumina particles were fluidized inside the deposition system using a mechanical vibration method. For the STEM analysis, the particulates were lightly crushed in water using a pestle and mortar, then diluted in ethanol and deposited on a TEM grid coated with an amorphous carbon thin film.

The feeding of spittlebug nymphs (Philaenus spumarius) from mature xylem vessels was studied by optical and cryo-analytical scanningelectron microscopy. Feeding did not produce xylem embolisms and vessels remained liquid-filled during the day. Saliva secreted by the insect forms a hardened lining (salivary sheath) between the stylet bundle and the plant tissues. This sheath is continuous through the hole made by the stylets as they enter a vessel, and it extends into the vessel and along its periphery beyond the breach. The sheath is heterogeneous, with a thin outer layer adjoining the plant tissues and a thicker layer that contacts the stylet bundle. Both layers give positive histochemical reactions for proteins and, in fresh tissues, contain a red, strongly autofluorescent pigment, possibly condensed tannin derived from the plant (which is lost during tissue preparation), and other phenyl propanoid compounds, which are retained and which may produce the intense reaction of the periodic-acid-Schiff's-positive inner layer. It is concluded that the salivary sheath allows the insects to feed from functioning vessels without embolizing them or losing xylem fluid to the surrounding tissues. These findings and others in the entomological literature indicate low daytime tensions in the xylem conduits of the host plants. PMID:21684926

Microvesicles are sub-micron structures shed from the cell membrane in a final step of the budding process. After being released into the microenvironment they are free to move and carry signaling molecules to distant cells, thereby they represent a communication system within the body. Since all cells shed microvesicles, it can be expected that they will be found in different body fluids. The potential diagnostic value of microvesicles has been suggested, however, a standardized protocol for isolation has not yet been agreed upon. It is unclear what is the content of the isolates and whether the isolated microvesicles were present in vivo or-have they been created within the isolation procedure. To present evidence in this direction, in this work we focus on the visualization of the material obtained by the microvesicle isolation procedure. We present scanningelectronic microscope images of microvesicles isolated from blood, ascites, pleural fluid, cerebrospinal fluid, postoperative drainage fluid and chyloid fluid acquired from human and animal patients. Vesicular structures sized from 1microm downto 50nm are present in isolates of all considered body fluids, however, the populations differ in size and shape reflecting also the composition of the corresponding sediments. Isolates of microvesicles contain numerous cells which indicates that methods of isolation and determination of the number of microvesicles in the peripheral blood are to be elaborated and improved. PMID:20199878

The aim of this study was to analyze, under scanningelectron microscopy (SEM), the morphologic characteristics of root surfaces after application of Carisolv gel in association with scaling and root planing (SRP). Sixty periodontally compromised extracted human teeth were randomly assigned to 6 groups: 1) SRP alone; 2) passive topical application of Carisolv + SRP; 3) active topical application of Carisolv + SRP; 4) multiple applications of Carisolv + SRP; 5) SRP + 24% EDTA; 6) topical application of Carisolv + SRP + 24% EDTA. Carisolv gel was applied to root surfaces for 30 s, followed by scaling and root planing, consisting of 50 strokes with Gracey curettes in an apical-coronal direction, parallel to the long axis of the tooth. The only exception was group 4, in which the roots were instrumented until a smooth, hard and glass-like surface was achieved. All specimens were further analyzed by SEM. The results showed that the treatment with Carisolv caused significant changes in root surface morphology of periodontally compromised teeth only when the chemical agent was actively applied (burnishing technique). Carisolv failed to remove the smear layer completely, especially with a single application, independently of the method of application. Multiple applications of Carisolv were necessary to achieve a smear layer reduction comparable to that obtained with 24% EDTA conditioning. PMID:16924336

Aim: The purpose of present study was to investigate the scanningelectron microscopic alterations produced on scaled and root planed dentin surfaces after application of different etching modalities namely citric acid, tetracycline hydrochloride and ethylenediaminetetraacetic acid (EDTA). Materials and Methods: Eighty specimens of teeth were collected and categorized into four groups. In group 1, control group specimens were treated with normal saline for 3 min, group 2 specimens were treated with citric acid, group 3 specimens were treated with tetracycline hydrochloride for 3 min and group 4 specimens were treated with 15% EDTA. Results: Opening of dentinal tubules was seen in all specimens except for control group that was treated with normal saline. The total number of tubules seen was highest in citric acid group as compared to tetracycline hydrochloride and EDTA Group. The total number of patent tubule opening was highest in citric acid as compared to EDTA and tetracycline. The diameter of patent dentinal tubules in citric acid group was more than EDTA and tetracycline. Conclusion: The study showed that all the three agents were effective in removing the smear layer however number of patent and wider diameter dentinal tubules was seen in vitro best in citric acid than EDTA and then in tetracycline hydrochloride. Hence, citric acid group is more efficient than EDTA and tetracycline HCl group in removing the smear layer and in opening of number of patent dentinal tubules. PMID:26644718